What's your computer system and Firefox version?

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

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

My version of Firefox is 63.0.1.6877, running on a DELL XPS8700 in Windows 10 Pro

Opening in safe mode fixes everything: new tabs, windows and searches all work.

Dave

It could be the work of one of your add-ons, or it could be Hardware Acceleration. How to disable Hardware Acceleration {web link}

Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control> (Mac=<Command>) <Shift> A)

In the Add-ons Manager, on the left, select Extensions. Disable a few add-ons, then Restart Firefox.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All Of them.

If the problem continues, disable some more (restarting FF). Continue until the problem is gone. After, you know what group is causing the issue. Re-enable the last group ONE AT A TIME (restarting FF) until the problem returns.

Once you think you found the problem, disable that and re-enable all the others, then restart again. Let us know who the suspect is, detective.

Thanks Fred

Turning the hardware accelerator off let me do searches, but not new tabs or new windows. From searches though I could do both of those. Curious. Anyway I turned hardware acceleration back on.

Then I went to add-ons. The guilty party is Adblock Plus: disabling it fixes everything. Since the problem is new I will uninstall and reinstall it, and if that doesn't fix things I'll leave it disabled.

Dave

Hi Dave, thanks for your report. Adblock Plus has a lot of features, so check whether it has a popup blocker. Possibly that function is overly aggressive but you can still safely use the other features.

For more help on this, contact Adblock support.