Firefox connection issues

Hello,

I have a problem with Firefox on my Mac. I had to change my network settings on my computer to use a proxy server to get onto the web at one hotel. Since I have done this (in the hotel everything worked fine) firefox cannot open any other pages apart from https (secure pages) any more, despite the fact that I have removed the proxy server settings (I think I have), removed the network I used at the time and reinstalled firefox twice (and am generally not using a proxy server to connect to the web). Safari on the other hand has absolutely no problem, which surprises me, as I made the changes to the over all network settings and not to firefox settings....
Any ideas?

Thanks,

Matze