I don't see enough info to troubleshoot this; Can you post your Application and System logs as attachments?

(Event Viewer in your Administrative Tools; It should be in your Start Menu under programs, but if not, it's in the Control Panel; Switch to Classic View and look near the top. Once you get Event Viewer up, right-click on those logs, select "Save Log File as..." and save it as an .evt file and attach it. (Actually, it doesn't matter how you save it, since the other formats are human-readable, but I'd find it easier to search if I can import the .evt into my own Event Viewer)

EDIT: Actually, I do see one thing that could be causing a problem--ZoneAlarm is a known offender for causing buggy behavior on Windows systems--but there might be something in the Event Viewer that could help things along without requiring the purchase of a router to act as a hardware firewall. Although that is strongly reccomended if you have the cash, since routers are more secure than a software firewall and don't drain your system resources)