Comment 18 for bug 241609

This is still occurring. Ubuntu 8.04 Firefox 3.05. Had error message along with same symptoms above. However,
addon session manager worked, and I could easily navigate to search. Found the suggestion: 'sudo chown -R myusername.myusername .mozilla/firefox' which worked. For us noobs, just remember to replace 'myusername' with the same name you log into Ubuntu with....