Does it make any difference if you update extensions?

orange Firefox button (or Tools menu) > Add-ons > "gear" icon > Check for Updates

I think that only checks extensions hosted on the Mozilla Add-ons site.

The first two crash reports have several different Trusteer Rapport modules running, so you might check for updates to those from Trusteer.

They also mention Keyhook.dll which sounds as though it could be suspicious. You may want to run some supplemental scans. These three tools are highly regarded (and free):

• Malwarebytes Anti-malware : http://www.malwarebytes.org/products/malwarebytes_free
• SUPERAntiSpyware : http://www.superantispyware.com/
• AdwCleaner : http://www.bleepingcomputer.com/download/adwcleaner/ (ignore banner ads for other products)

The crash reports do not seem to implicate Flash, but since Flash is so pervasive on the web, a little Flash hygiene might be a good idea until this settles out.

This is some standard guidance that addresses the most common issues. I'm sure you've seen some of it before, but just in case:

(1) Make sure all recorders/downloaders that interact with Flash media are as up-to-date as possible, or disable them.

(2) Disable hardware graphics acceleration in Firefox and in Flash

(A) In Firefox, un-check the box here and restart:

orange Firefox button (or Tools menu) > Options > Advanced > General > "Use hardware acceleration when available"

(B) In Flash, see this support article from Adobe: http://helpx.adobe.com/flash-player/kb/video-playback-issues.html#main_Solve_video_playback_issues

(3) Disable protected mode (Windows Vista/7/8)

See this support article from Adobe under the heading "Last Resort": Adobe Forums: How do I troubleshoot Flash Player's protected mode for Firefox?

Thanks for your help!

- I've uninstalled Trusteer Rapport, since I now do my banking in a Linux VM, and the installation appeared to be clobbered anyway. - Keyhook.dll was from my USB KVM switch software; uninstalled. - I've updated everything that I can think of, and I run Secunia PSI to check for versions (it gives me 100% up to date). - I've disabled hardware graphics acceleration in both Firefox and Flash. - I've disabled protected mode in Flash as per the article you gave. - I've run both SuperAntiSpyware and CCleaner; the only issues were tracking cookies and the mangled Rapport installation.

So far, so good *knock on wood* :) I will mark this as resolved if the crashing continues to not happen for a day or so.

Thanks again!

Stable all day (previously it would have crashed shortly after being left unattended). Marked as solved, thanks again!