Slow and BSODs

I'm typing this from my phone because my pc is too unreliable. Pc boots up, after around 30 minutes to an hour the pc starts getting really slow, freezes, and then bsods. The bsod says, "a process or thread has unexpectadly stopped or has been terminated.".

The bsod doesn't actually write a dump though even though I have it setup correctly. Then after I turn the pc off and back on I can't boot because it says no harddrive is found. If I leave the computer off for awhile, then it will boot again, but the previous mentioned repeats again.

System specs:
AMD phenom II x4
4gb DDR2 ram
Nvidia GeForce
Asustek mobo

Is Windows 7 . . .
- x86 (32-bit) or x64 ? 64
- the original installed OS on the system? Yes
- an OEM or full retail version? Full retail version
- OEM = came pre-installed on system
- Full Retail = you purchased it from retailer

- What is the age of system (hardware)? 2 years
- What is the age of OS installation (have you re-installed the OS?) 3 months

Can someone please diagnose this problem. Thanks.

Even though you do not have a .dmp file, please follow the http://www.sevenforums.com/crashes-debugging/96879-blue-screen-death-bsod-posting-instructions.html to provide us with your system and application logs. Those may indicate what is causing the system to become unresponsive and eventually freeze.

Since your hard disk is not being detected on startup after crashes, check for hard disk errors and/or a faulty hard disk.

• Run Disk Check with both boxes checked for all HDDs and with Automatically fix file system errors checked for all SSDs. Post back your logs for the checks after finding them using http://www.sevenforums.com/tutorials/96938-check-disk-chkdsk-read-event-viewer-log.html.
  For any drives that do not give the message:
  Windows has checked the file system and found no problems
  run disk check again as above. In other words, if it says:
  Windows has made corrections to the file system
  after running the disk check, run the disk check again.
  
  
• Use the short and long tests of SeaTools to check the hard disk and determine whether it is working properly.

Ok I will, thanks.

You're welcome. Post back if you need help or further steps.

Also, let us know the results of those tests.