Have a serious network adapter problem...need help!

OK well i have a Dell 3.2ghz with 1gb ram and a geforce 6800. My network adapter is a PRO/1000 PL network connection. After the computer has been on for a couple of hours, something happens to it. All of a sudden the internet stops working. Whenever i try to run a program that connects to the internet (an online game) it has a message saying not enough buffer space avaliable. Then if i try to run the taskmanager (CTRL+ALT+DEL) a message pops up saying the program failed to initilize 0x00000017. Now for some reason everything on the computer has an error message. Now to make the computer act normal i have to disable the network adapter...this makes the computer act normal again. So something is wrong with the network adapter and it is causing my computer and internet to malfuntion...i dont know what. I checked on the intel website but it had nothing on the PRO/1000 PL! What is wrong? It is very frustrating. Right now the only way to fix it when the network adapter does this is to restart the computer...but i lose all of my work everytime! i REALLY need to find a solution and to fix this problem.

Is it set to power the nic down maybe?
Go to Control Panel, network conections and then right click the intel nic and choose properties.
Then configure at the top then Power management. If its set to power the nic down automatically, uncheck that