COMPUTER ONLY STARTS IN SAFE MODE

Hello,


I have a computer that is about two years old, running Windows Vista, 32-bit. I apologise in advance, I am trying to give you all the stuff that you need to hopefully help me fix me problem. About four weeks ago, my computer was running fine. I have a Pentium Dual Core Processor. My boyfriend went to play a game, and the computer screen started flashing really fast, and acting all weird. The screen would go blue, but it was different from the BSOD. I got it back up and running with just a re-start. After that, my internet, and computer in general just started running really slow. And it would freeze constantly, and take so long to start up and shut down. Thinking that I may have a virus, I did a virus scan with Commodo Internet Security, and it showed nothing, not even a piece of spyware. After that, I thought it may have been a program that I recently downloaded, so I deleted everything that I did not get with the computer when I bought it. And it was still running slow. It was time for the computer to be cleaned, so took the case off, which I have done at least twenty times, and cleaned the inside of the computer. There was some dust in there, so I cleaned it, with compressed air, and put it back together. Upon re-starting, I got an error message that it could not find Windows, and I could not log in at all. So I called my tech support, that came with the computer and after five frustrating hours, they said my only option was to format my hard drive and do a clean install of Vista. I have since done that, and lost everything. I expected that to fix my problem, but now the computer is still running slow. I can get it to run fairly quickly in safe mode, and I have tried disabling start up programs, and re-enabling them as well as all the diagnostics that Windows offers. I would appreciate any help you can offer, and if you require anything else to help me, please let me know.