Thunderbird and Mozilla Seamonkey - Cannot use the profile 'xyz' because it is in use

Long ago, if you had a crash[1] and restarted Mozilla, you'd get an error that your profile is in use even when it blatantly isn't.

What you'd do, is look in /home/me/.mozilla/randomstring/ and delete the "lock" file. Not so in new versions.

Now you need to delete lock, but also a hidden file called ".parentlock". That took a long time to find and makes me glad I use Opera for my day to day browsing, which has never taken a long time to get running again after a rare failure.

Thunderbird is a reasonably good email client, but really it is the best of a bad bunch. Anyone who once lived for Fido using Amiga software will realise just how bad an experience email is today. I think perhaps it is the Outlook experience many suffer in the workplace which has lowered expectations so much.

[1] Upgraded Kspread. It took ownership of ODF spreadsheets from OpenOffice in KDE. I tried to open a spreadsheet, Kspread opened and my machine was reduced to a gibbering wreck as it consumed all resources (swap usage). That is only software I know that can cause an effective lockup from unprivileged user mode in Linux.