The STOP 0xF4 error is a bear to troubleshoot, but considering the other errors you've had I'd have to suspect your hard drive.
Here's some basic info on the STOP error: http://aumha.org/a/stop.php#0xf4
And here's some more specific info from the Windows Debugging Tools:
Bug Check 0xF4: CRITICAL_OBJECT_TERMINATION
The CRITICAL_OBJECT_TERMINATION bug check has a value of 0x000000F4. This indicates that a process or thread crucial to system operation has unexpectedly exited or been terminated.
The following parameters are displayed on the blue screen.
1 The terminating object type:
2 The terminating object
3 The process image file name
4 Pointer to an ASCII string containing an explanatory message
Several processes and threads are necessary for the operation of the system. When they are terminated for any reason, the system can no longer function.
This tells us that it was a process (parameter 1) that terminated, and that the process was located at 0x89b17b54 (parameter 3)
You can tell a bit more about it by capturing the memory dump and running it through the Windows Debugging Tools (more info on how to do that here: http://usasma.vox.co...ed-02oct08.html
But, since there's some indication that this may be the hard drive, the memory dump files may not reveal anything significant.
I'd suggest running the Recovery Console ( http://www.bleepingc...utorial117.html
). Once in the Recovery Console, try typing the command "chkdsk /r" (without the quotes) and pressing Enter. Let it run and tell us if it shows any errors being repaired.
Beyond that, you can also run a bootable hard drive diagnostic. This is available from the website of your hard drive manufacturer and is usually free.