Seems that FF3 has a slight problem with cache handling due to anti-phishing algorythms. I found this somewhere on the net, and it really works.

Go to FF preferences -> Security and un-check 2nd and 3rd checkbox,
“Tell me if …”

Close preferences and close Firefox.
Go to your users settings where firefox keeps it’s files for the account. I Windows should be somewhere in “Application Data”, I am not sure, but for Linux, open terminal and write
#> cd .mozilla/firefox
and enter in tou your account directory (should be something like “of6wel65.default”) , name is pretty random.

- Delete files urlclassif*.sqlite
- Start firefox.

that is it.