Comment 8 for bug 73457

I had this same problem, both with Firefox and Thunderbird. I noticed the following:

- all the problems began when I tried to point my Ubuntu profiles to my XP profiles
- both apps worked fine in XP the whole time
- as soon as I switched my profiles back to the Ubuntu partition, I could use both apps again

Looking around, I found one site that instructed me to create a FAT32 partition to store my profiles on so that both OSs could use them. This led me to believe that the problem was with Ubuntu's ability (or lack thereof) to write onto XP's NTFS partition, where all my files are still stored.

So, I did some looking around and came across this guide to letting Ubuntu write onto NTFS:

DISCLAIMER: I am very new to Ubuntu and cannot promise that this will work.
http://ubuntuforums.org/showthread.php?t=217009

After following that guide both programs worked perfectly. My Firefox extensions from XP even work in Ubuntu still!

Hope that helps.