You can imagine my relief when I came across this post by Kevin Tofel:
Got a note from good friend Jordan today and I think it explains why I'm seeing Firefox 3 crash a half-dozen times daily on my Samsung Q1UP. Based on his conversations with the Mozilla folks and the related Bugzilla info, there appears to be a known issue with Firefox 3 and Tablet PCs (both XP and Vista). That could explain why many folks have the browser running rock-solid, while others, like Jordan and his X61, are fighting with constant crashes.I just downloaded the beta version of Firefox 3.0.1 last night and so far the problem seems to have been solved. I am now another very happy user of Firefox 3.0.
I've just installed the latest beta candidate of Firefox 3.0.1 where this particular issue is addressed and since I'm still not using client applications other than the browser, I should know in a few hours if this build is any better. Worst case: I can always go back to the production version of FF3 if the issue isn't fixed or other issues are introduced. Remember this is a beta candidate, so caveat emptor! Thanks for the tip, Jordan!
It's not clear in the link above which file you should install. It took me a bit of digging and reading through the comments on the post to figure out you want to use firefox-3.0.1.en-US.win32.installer.exe if you're in the US, using American English.
Who would have thought the problem was that I was using a Tablet PC?