Whenever i leave my computer on for an extended period of time without use (eg. sleeping or school), my internet seems to get disconnected.
When i come back from say sleep or school, i come to find my wlm disconnected, then when i try to surf the net, nothing shows up (eg. Server cannot be found error), even though it says that my Local Area Connection (which is my main connection) is connected. From then on i cannot access anything that uses the internet unless i restart my computer.

Does anyone know a way to fix my problem?

If you have Vista on. It would be one of the power saving features. Go to Control Panel\Power Options, then click "change plan settings". Then click "change advanced power settings"

Dont have Vista, have XP, and my power scheme is set to "Always On"