Internet Security Software Issues
Internet Security software is designed to protect you from hackers but sometimes it can hinder you as well. If you are having issues with the internet or email. Try disabling the internet security software (don't forget Windows XP SP2 has a firewall also).
If the problem goes away with it disabled, the problem is with the software. Try uninstalling the software and then reinstalling the software. Go to Add/Remove Programs and remove it from there. If it won't remove from their go to the manufacturer of the internet security software and see if they have a removal tool to remove the software.
If the problem continues with it disabled, go to safe mode with networking (Windows XP) and see if it works there. If it does work there it can still be the internet security software. Try removing and reinstalling the software.