XP Hangs

[dondon]

I have Windows XP PRO with all critical updates.Every thing was fine but all of a sudden whenever I connect to the internet the computer hangs and the only way out of it is to reset the computer.
I tried uninstalling and reinstalling the network card and modem & USB but to no avail.So then I tried to install a ISDN external USB Modem but it totally hangs again during the installation.Does anyone have any ideas?

[Cricket]

Have you scanned for viruses, trojans, spyware and malware yet?

:) Cricket