Need experienced person for help

Hey I am in need for assistance. A few days ago my computer was running very slow so my brother tried to tweak it up a bit. He first download windows service pack 2. After restarting the computer all these errors popped up and the computer crashed. We than recently reformatted the whole hardrive and did our usual by installing windows professional and all of our needed programs and software. After that I installed a windows update and it told me to restart my computer so i did so. While it was loading up it came to a blue screen where it was doing some diskcheck which i thought was nothing. after it went through that errors kept popping up all over the place saying stuff like could not sace :C Program files or documents and many other files and said the files have been lost. In the same errors it also said this could be due to corrupt or bad hardware or the network connection. My brother said it could be the hardrive or the network card or whatever on the back of the computer. If anyone could respond and help me that would be great.

P.S. A day before this all happened I dusted out my computer but I think a lot of the dust i tried getting out went straight into where the hardrive is. And after this inccident i opend the front of the computer up and it was filled with dust. Im not sure if Its the hardrive or the network card.

 

Not sure if i can help, but open your case, and disconnect all of your peripherals that are not ESSENTIAL, except the network card. try to boot into safe mode with netowrking, and download SP2. reboot normally, and see if you get any errors. If so, post back, and someone else may have some ideas.