I have three "profiles" I use for firefox (a general one, a work one, and a locked down one). I can load them with the "-P" option on the command line just fine. If no firefox is running, then any one of them will work fine. So, I think I've got the basics working right. However, two of the profiles (work and general) won't run at the same time. But the locked down one will run with either of the other two. I can't figure out why and am looking for hints on logs to enable or debug levels to turn up, or settings to tweak inside (or outside) the profiles. Specifically, by "won't run", I mean that if the 'general' profile firefox is up and running, then if I start my work profile (i.e., "firefox -P work"), it just opens a new window on the current general profile. If I open the locked-down profile (i.e., "firefox -P lockdown") that comes up fine (starts a separate instance of firefox, with its own plugins and whatnot). I've had this problem for a long time (lots of version of Firefox, even before 3.0, I think). I only have this problem on Windows (but both WinXP and now Win7). I'm comfortable tweaking settings and looking through logs, but am not sure what to enable. Google searches haven't been fruitful (there seem to be relatively few folks using Firefox Profiles).