Internet goes off after a while!

My internet goes off or crashes after i use my computer for about 3-5 hours.

It says im still connected but when i open a web page on firefox, opera, internet explorer, or an internet based application, it says server not found. (could not connect to page). Like if I'm Offline!!!

This started happening after i did 2 of the following things:

1. Installed then Uninstalled Pearl. (The program pearl for coding.)
2. I also installed the same day the driver for my Ethernet and mobo driver.

This happens when im connecting to the internet via Ethernet, and ALSO when connecting wireless using a wireless USB receiver.

Can someone tell me what could be causing this?

Thanks!!!!