Ubuntu :: All Applications Crashing - Firefox, Thunderbird, Opera, OpenOffice?

For a couple of weeks, I have had constant crashes of all my applications on Lucid:Thunderbird 3.1 (updated since crashing started using Ubuntuzilla)Firefox 3.6.6 (updated since crashing started using Ubuntuzilla) - also crashes in safe mode OpenOffice 3.2 Opera 9.63 Most frequently it is Firefox and Thunderbird crashing, because they're the applications I use most. (Also F-Spot has crashed, but F-Spot frequently crashed before all this, so may not be related).

Sometimes applications will run for a few hours and then crash (either suddenly close or freeze, it varies). Other times the application crashes before it even opens, and I just get the Mozilla crash reporter. If an application won't start at all, it will usually start if I restart the computer, but may crash again soon afterwards. There is no obvious pattern to when it crashes - sometimes on starting, sometimes when I click something, sometimes when I'm not even at the computer and I just come back to find it crashed.

My husband (a programmer) has run Memtest on my machine, which found no problems. He is also running lucid on the same hardware apart from the monitors, and has the same versions of OpenOffice, Thunderbird and Firefox except for extensions, but has not any problems. A warning that shows on the terminal if Firefox crashes in safe mode, is:

WARNING: pipe error: Broken pipe: file /builds/slave/linux_build/build/ipc/chromium/src/chrome/common/ipc_channel_posix.cc, line 627
WARNING: pipe error (3): Connection reset by peer: file /builds/slave/linux_build/build/ipc/chromium/src/chrome/common/ipc_channel_posix.cc, line 404

This is strange because I did not, when that warning first appeared, have Chromium installed (although I did have Picasa). My husband installed Chromium on my machine after seeing the warning and Chromium is running okay so far but other applications are still crashing.