Thanks for giving me the link via Twitter. :) Also, you should've posted your information. In order to be able to find the correct solution to your problem, we require some more non-personal information from you. Please do the following:

• Click the Firefox button at the top left, then click the Help menu and select Troubleshooting Information from the submenu. If you don't have a Firefox button, click the Help menu at the top and select Troubleshooting Information from the menu.

Now, a new tab containing your troubleshooting information should open.

• At the top of the page, you should see a button that says "Copy text to clipboard". Click it.
• Now, go back to your forum post and click inside the reply box. Press Ctrl+V to paste all the information you copied into the forum post.

If you need further information about the Troubleshooting information page, please read the article Use the Troubleshooting Information page to help fix Firefox issues.

Thanks in advance for your help!

Application Basics
------------------
Name: Firefox
Version: 27.0.1
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:27.0) Gecko/20100101 Firefox/27.0
Crash Reports for the Last 3 Days
---------------------------------
All Crash Reports
Extensions
----------
Important Modified Preferences
------------------------------
browser.cache.disk.capacity: 358400
browser.cache.disk.smart_size.first_run: false
browser.cache.disk.smart_size.use_old_max: false
browser.cache.disk.smart_size_cached_value: 358400
browser.places.smartBookmarksVersion: 4
browser.sessionstore.upgradeBackup.latestBuildID: 20140212131424
browser.startup.homepage_override.buildID: 20140212131424
browser.startup.homepage_override.mstone: 27.0.1
dom.mozApps.used: true
extensions.lastAppVersion: 27.0.1
gfx.direct3d.last_used_feature_level_idx: 0
network.cookie.prefsMigrated: true
places.history.expiration.transient_current_max_pages: 77097
plugin.disable_full_page_plugin_for_types: application/pdf
plugin.importedState: true
privacy.sanitize.migrateFx3Prefs: true
Graphics
--------
Adapter Description: Intel(R) HD Graphics Family
Adapter Drivers: igdumd64 igd10umd64 igd10umd64 igdumdx32 igd10umd32 igd10umd32
Adapter RAM: Unknown
Device ID: 0x0116
Direct2D Enabled: true
DirectWrite Enabled: true (6.2.9200.16571)
Driver Date: 1-27-2011
Driver Version: 8.15.10.2291
GPU #2 Active: false
GPU Accelerated Windows: 2/2 Direct3D 10
Vendor ID: 0x8086
WebGL Renderer: Google Inc. -- ANGLE (Intel(R) HD Graphics Family Direct3D9Ex vs_3_0 ps_3_0)
windowLayerManagerRemote: false
AzureCanvasBackend: direct2d
AzureContentBackend: direct2d
AzureFallbackCanvasBackend: cairo
AzureSkiaAccelerated: 0
JavaScript
----------
Incremental GC: true
Accessibility
-------------
Activated: false
Prevent Accessibility: 0
Library Versions
----------------
NSPR
Expected minimum version: 4.10.2
Version in use: 4.10.2
NSS
Expected minimum version: 3.15.4 Basic ECC
Version in use: 3.15.4 Basic ECC
NSSSMIME
Expected minimum version: 3.15.4 Basic ECC
Version in use: 3.15.4 Basic ECC
NSSSSL
Expected minimum version: 3.15.4 Basic ECC
Version in use: 3.15.4 Basic ECC
NSSUTIL
Expected minimum version: 3.15.4
Version in use: 3.15.4

Did you check for issued caused by security (anti-virus) software?

Try to rename (or delete) the mimeTypes.rdf file in the Firefox profile folder to reset all file actions.

• http://kb.mozillazine.org/mimeTypes.rdf
• http://kb.mozillazine.org/File_types_and_download_actions#Resetting_download_actions

What is the error that happens when you try to download .rar or .zip file?

please provide us with a screenshot. If you need help to create a screenshot, please see How do I create a screenshot of my problem?

Once you've done this, attach the saved screenshot file to your forum post by clicking the Browse... button below the Post your reply box. This will help us to visualize the problem.

Thank you!

Here is the error.

Try cor-el's advice above then report back.

The problem persists.

What rar file are you trying to download? Can you give me a link to it?

It happens with all .RAR or .Zip files.

Any other suggestions?

No idea what was causing the problem. But I apparently solved it.

Additionally: Firefox won't download previously failed .RAR files unless you delete the .part files in your Downloads folder and the instances of the files in your "Recent Files" folder.

Ok apparently I didn't solve it.

Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• TDSSKiller - AntiRootkit Utility
• Hitman Pro
• ESET Online Scanner

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one.

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

Did this fix your problems? Please report back to us!