Internet connection

I am running OS X .3 on a G4, my server is BT internet and I am using an Alcatel Speedtouch
USB broadband modem. Occasionaly when on the internet and using Safari changing from one web page to another it will freeze, if I try Netscape or IE Explorer nothing moves, although the
computer itself behaves normally, to solve this I have to remove the modem usb plug and re-insert it, wait for it to cinque up and then re-connect. I have zeroed all data and re-installed the
software, also installed the latest modem drivers, but still have this problem, I think since I installed Panther. Has anyone else come across this problem? or does anyone know the cause and solution?