Torbutton's startup component sometimes doesn't load (no cache isolation)
I just had a weird error with TBB 3.0a3 on Linux. According to about:cache, my cache was not being isolated with any domain= keys, and I wasn't getting any 'SSC" isolation log messages. I restarted a couple times and tracked it down to the Torbutton startup-observer.js component not loading for some reason, with no exceptions in the log window about it. I installed XPCOM viewer to see if it was even registered, and then it suddenly started working again after that restart...
Scary :/.