Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac Options) key, and then starting Firefox.

Now open the Add-ons Manager. Are your add-ons listed (but disabled) ?

Type about:support in the address bar and press Enter. Under the main banner, press the button; Copy Text To Clipboard.. Then in the reply box at the bottom of this page, do a right click in the box and select Paste. This will show us your system details. No Personal Information Is Collected.

After losing the add-ons this last time I just went ahead and searched for LastPass then reinstalled it, when I restarted the browser, it prompted me as shown in the screenshots and I accepted installation.

I'll need to wait for the extensions to disappear again before I can restart in safe mode to confirm whether they exist in safe mode when they disappear from the extensions tab when running in normal (non-safe mode). I believe last time I started in safe mode, the extensions were also missing there when they were missing from the normal mode.

Application Basics

Name: Firefox Version: 42.0 Build ID: 20151029151421 Update Channel: release User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:42.0) Gecko/20100101 Firefox/42.0 Multiprocess Windows: 0/2 (default: false) Safe Mode: false

Crash Reports for the Last 3 Days

All Crash Reports (including 2 pending crashes in the given time range)

Extensions

Name: Evernote Web Clipper Version: 6.0.15.1-signed Enabled: true ID: {E0B8C461-F8FB-49b4-8373-FE32E9252800}

Name: FiddlerHook Version: 2.6.0.4 Enabled: true ID: fiddlerhook@fiddler2.com

Name: History Janitor Version: 1.2.1-signed Enabled: true ID: history-janitor@ednovak.net

Name: LastPass Version: 3.2.21 Enabled: true ID: support@lastpass.com

Name: Lazarus: Form Recovery Version: 2.3.1-signed Enabled: true ID: lazarus@interclue.com

Name: NoScript Version: 2.6.9.39 Enabled: true ID: {73a6fe31-595d-460b-a920-fcc0f8843232}

Name: Restart Version: 1.2.7 Enabled: true ID: Restart@schuzak.jp

Name: The Camelizer - Price Tracker Version: 2.8.1 Enabled: true ID: izer@camelcamelcamel.com

Name: Torrent Status Version: 2.0 Enabled: true ID: {b8eb6570-dd49-11df-937b-0800200c9a66}

Name: uBlock Version: 0.9.5.0 Enabled: true ID: {2b10c1c8-a11f-4bad-fe9c-1c11e82cac42}

Graphics

Adapter Description: NVIDIA GeForce GTX 780 Adapter Description (GPU #2): NVIDIA GeForce GTX 570 Adapter Drivers: nvd3dumx,nvwgf2umx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um,nvwgf2um Adapter Drivers (GPU #2): nvd3dumx,nvwgf2umx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um,nvwgf2um Adapter RAM: 3072 Adapter RAM (GPU #2): 1280 Asynchronous Pan/Zoom: none Device ID: 0x1004 Device ID (GPU #2): 0x1081 Direct2D Enabled: true DirectWrite Enabled: true (10.0.10240.16430) Driver Date: 10-2-2015 Driver Date (GPU #2): 10-2-2015 Driver Version: 10.18.13.5850 Driver Version (GPU #2): 10.18.13.5850 GPU #2 Active: false GPU Accelerated Windows: 2/2 Direct3D 11 (OMTC) Subsys ID: 07843842 Subsys ID (GPU #2): 0000000c Supports Hardware H264 Decoding: true Vendor ID: 0x10de Vendor ID (GPU #2): 0x10de WebGL Renderer: Google Inc. -- ANGLE (NVIDIA GeForce GTX 780 Direct3D11 vs_5_0 ps_5_0) windowLayerManagerRemote: true AzureCanvasBackend: direct2d 1.1 AzureContentBackend: direct2d 1.1 AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0 (#0) Error: [D2D1.1] 4CreateBitmap failure Size(28,25287) Code: 0x80070057 format 0 (#1) Error: [D2D1.1] 4CreateBitmap failure Size(28,25287) Code: 0x80070057 format 0 (#2) Error: [D2D1.1] 4CreateBitmap failure Size(28,25287) Code: 0x80070057 format 0

Important Modified Preferences

accessibility.typeaheadfind.flashBar: 0 browser.cache.disk.capacity: 358400 browser.cache.disk.filesystem_reported: 1 browser.cache.disk.smart_size.first_run: false browser.cache.frecency_experiment: 1 browser.download.importedFromSqlite: true browser.download.manager.alertOnEXEOpen: true browser.places.smartBookmarksVersion: 7 browser.sessionstore.upgradeBackup.latestBuildID: 20151029151421 browser.startup.homepage_override.buildID: 20151029151421 browser.startup.homepage_override.mstone: 42.0 dom.apps.reset-permissions: true dom.mozApps.used: true extensions.lastAppVersion: 42.0 gfx.direct3d.last_used_feature_level_idx: 0 gfx.driver-init.appVersion: 42.0 gfx.driver-init.deviceID: 0x1004 gfx.driver-init.driverVersion: 10.18.13.5850 gfx.driver-init.feature-d2d: true gfx.driver-init.feature-d3d11: true gfx.driver-init.status: 2 media.gmp-eme-adobe.abi: x86-msvc media.gmp-eme-adobe.lastUpdate: 1447447009 media.gmp-eme-adobe.version: 15 media.gmp-gmpopenh264.abi: x86-msvc media.gmp-gmpopenh264.lastUpdate: 1447447009 media.gmp-gmpopenh264.version: 1.4 media.gmp-manager.buildID: 20151029151421 media.gmp-manager.lastCheck: 1447540358 media.hardware-video-decoding.failed: false network.cookie.prefsMigrated: true network.predictor.cleaned-up: true places.database.lastMaintenance: 1447363941 places.history.expiration.transient_current_max_pages: 104858 plugin.disable_full_page_plugin_for_types: application/pdf plugin.importedState: true privacy.sanitize.migrateFx3Prefs: true storage.vacuum.last.index: 1 storage.vacuum.last.places.sqlite: 1447363941

Important Locked Preferences

JavaScript

Incremental GC: true

Accessibility

Activated: false Prevent Accessibility: 0

Library Versions

NSPR Expected minimum version: 4.10.10 Version in use: 4.10.10

NSS Expected minimum version: 3.19.4 Basic ECC Version in use: 3.19.4 Basic ECC

NSSSMIME Expected minimum version: 3.19.4 Basic ECC Version in use: 3.19.4 Basic ECC

NSSSSL Expected minimum version: 3.19.4 Basic ECC Version in use: 3.19.4 Basic ECC

NSSUTIL Expected minimum version: 3.19.4 Version in use: 3.19.4

Experimental Features

It is possible that there is a problem with the file(s) that store the extensions registry.

Delete the extensions.* files (e.g. extensions.json, extensions.sqlite, extensions.ini) and compatibility.ini in the Firefox profile folder to reset the extensions registry.

• https://support.mozilla.org/kb/Profiles

New files will be created when required.

See "Corrupt extension files":

• http://kb.mozillazine.org/Unable_to_install_themes_or_extensions
• https://support.mozilla.org/kb/Unable+to+install+add-ons

If you see disabled or not compatible extensions in "Firefox menu button/Tools > Add-ons > Extensions" then click the Tools button at the left end of the Search bar to check if there is a compatibility update available.

If this hasn't helped then also delete the addons.json file.

I closed firefox and deleted extensions.json and extensions.ini, there was no extensions.sqlite. I went ahead and removed compatibility.ini as well as addons.json.

It takes some time for the issue to present itself. I haven't really timed it or tried really hard to take notice of any event that may cause it to happen. I also don't notice right away because I don't go into manage my addons that often, so I can't be sure of when the issue appeared. Sometimes it takes a day or two, so I will mark as resolved if the issue doesn't occur again in a day or two.

Are you running any cleanup software that is scheduled to run regularly that might be causing this issue?

Lcstyle said

Crash Reports for the Last 3 Days

All Crash Reports (including 2 pending crashes in the given time range)

Some of your crash reports weren’t sent to the Mozilla Servers.

In the address bar, type about:crashes<enter>. Note: If any reports do not have BP in front of the numbers/letters, click it and select Submit.

The crash report is several pages of data. We need the report numbers to see the whole report.

I followed the steps above, but unfortunately, cannot confirm the fix for the root cause.

You see I discovered I had some kind of malware called "malware protection live". It appears in the form of a very nicely rendered and "official looking" Check Mark in your system tray, so I didn't notice it.

I think that this malware was trying to install somethin into FF, whether it's own addon "surreptitiously" or trying to inject some other binary into FF, and perhaps corrupting the firefox addon files.

Since the issue has not happened since I performed your recommended steps to remove those files and cleared the malware from my system, I suggest we close this one as resolved.

FredMcD said

Lcstyle said

Crash Reports for the Last 3 Days

All Crash Reports (including 2 pending crashes in the given time range)

Some of your crash reports weren’t sent to the Mozilla Servers.

In the address bar, type about:crashes<enter>. Note: If any reports do not have BP in front of the numbers/letters, click it and select Submit.

The crash report is several pages of data. We need the report numbers to see the whole report.

I went ahead and clicked on the few (relatively) recent ones that were unsubmitted FYI.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.