Simple cleaning job, becomes a nightmare

[Kalidas]

As the thread states this is all started with a very simple cleaning job. I just wanted to clean the dust out of my pc with some of that pc can air stiff.

Well I did something not very smart(I realize my mistake now). I removed the heat sink to get to as much dust as possible. But like an idiot I did NOT add new thermal paste. Plugged everything back in and booted the pc up. No problems,actually was running quicker than usual (it was REALY dusty). Then it shutdown, this happened about 3 times before I looked up the issue, bought some paste and applied it. It booted I ran real temp to be sure the heating was fine and it hovered atound 40-48c depending on the activity. It would run fine for about 2 or 3 hours and then crash. This happened about 3 times and then things got really bad.

Now it takes HOURS to boot. Always asks for startup repair, always runs a dskchk. One time I sat and waited for hours to get into the pc, it ran fine after that long boot up time, but ran regular after that. I checked the system errors and deleted some programs that were causing errors and slow boot time(no windows files just things like apps or programs nothing crucial). So I shut it down to see if that worked. Nope ever since than I have not been able to get into the pc. Boot up takes up to 6 hours. Sits at "starting windows" alone for 2 hours. Then there are the start up repairs, dskchks, and I get to the profile select and it just goes to black(I can see and control the mouse)and just never loads anything.

So at this point there are 3 things I think could be the problem. Motherboard, harddrive, or the cpu(oh please Gods let this not be the case.)
Any advice troubleshooting tips, or general knowledge is much appreciated.

CPU is listed here http://m.newegg.com/Product/index?itemnumber=N82E16819115072

Motherboard
http://m.newegg.com/Product?itemNumber=N82E16813138357

Windows 7

Its a custom pc. If you need any more info let me know. Thanks in advance for any help you offer.

 

[IamTimTech]

Your hard drive is failing. Confirm with Western Digital Diagnostic tools.

If your PC is still posting and if it is still running fine when it gets booted then your processor very unlikely to be damaged. Same fro your motherboard.

 

[Kalidas]

Yeah hard drive seemed like the most likely situatuon. All those force shutdowns can really ruin a hard drive. Its gotten to the point where I cant even get into my computer profile. Which makes the harddrive seem even more likely.

What I mean by I cant get into my profile is at the windows screen where it should say "my name pc" it just says "computer". My personal profile is entirely missing.

 

[IamTimTech]

The fact that it wants to check the disc for errors at boot is the give away. A processor failure most often results in different symptoms. You should stop trying to boot up so that you can retrieve your data with the hard drive in another system as the sectors with the O.S. are usually the first ones to go, not the user files.