Problem GPU on my Acer 5520-5912

Hello Community, i have a problem with my Acer 5520-5912. it has everything stock. i have only change on thing about it and it was the Operating system. i had Vista but installed XP black.

earlier before had this problem i had installed a pc game called G force. it had a crack and everything but idk what it would have to do with the Graphics card. while i was trying to install the program it said i needed directx 9.0c and that it was going to be installed.

i cannot go online for a long time. when i boot my computer it takes a while longer. my computer freezes more often. it did not use to freeze at all before. but after it is done freezing it the computer tries to restart itself but then the whole screen goes pitch black and then it says in the blackened screen:

Nvidia Boot Agent 249.0542
Copyright (c) 2001-2005 Nvidia Corporation
Copyright (c) 1997-2000 Intel Corporation
PXE-E61: media test failure, check cable
PXE-MOF: Exiting Nvidia Boot Agent

then it repeats this about ten times like it is trying to check the Graphics card for something. then it shuts off.

i tried removing all the files that i had put in my computer of the G force game and it will not let me remove it. i cannot be on the computer for too long. when it get hot it does the same thing. when i go online it freezes up faster no matter what. i have another account on the computer and i logged on and it was fine for a few minutes but it did the same thing.

i need your help what should i do?

yah i think so too. hey how do i record my temp. for my computer? i had it for about a year and a half already.

thank you for your help