It turns out that it is happening still but we're still mystified. See my earlier comment for a possible way of finding out what is creating this file.
** Changed in: firefox (Ubuntu) Status: Fix Released => Needs Info -- firefox 1.4.99 upgrade still have compreg.dat, creates issue https://launchpad.net/bugs/30791 -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs