Have you disabled the Shockwave Flash plugin as part of your diagnosis? Very thorough.

Are you getting any of the Mozilla Crash Reporter dialogs, or are you only getting dialogs from Windows, or is Firefox hanging and requiring you to "kill" it?

When Firefox crashes rather than being terminated externally, it usually records information about what was happening at that moment. You can submit that data to Mozilla and share it with forum volunteers to see whether it points to the solution. Please check the support article "Firefox Crashes" (especially the last section) for steps to get those crash IDs, and then post some of the recent ones here.

Also, could you try disabling Firefox's use of hardware acceleration for graphics? This feature is sensitive to graphics card driver changes and incompatibilities can cause symptoms from display aberrations to blue screen crashes. I don't know whether this is relevant in your case, but it's worth a try.

orange Firefox button (or Tools menu) > Options > Advanced

On the "General" mini-tab, uncheck the box for "Use hardware acceleration when available"

This will take effect after you exit and restart Firefox.

I've disabled hardware acceleration and just removed Shockwave.

The most recent crash dump is Crash ID: bp-37b441d3-0742-4922-8bdc-4dc1a2140131

Hi ResolverBob, thanks for the new crash report.

I don't understand most of it, but "oom" indicates an Out of Memory condition, and the report shows that physical memory was 90% full. If you typically keep over 100 tabs open, you may be pushing the limits of Firefox's ability to use memory. Or you may have found a site that exposes a problem in Firefox's ability to properly manage memory. I don't have any specific recommendations on this one.