If it's a fresh install and it's still freezing, then it's 100% a HARDWARE issue. The following problems can cause this issue:
1) Faulty ram. The ram hasn't completely failed yet, but when it has data written to the bad part of it, your system freezes. Best way to test: If you have multiple ram chips, take out one, and see if the system stalls, if it doesn't you know the one you took out is faulty and replace it, if it still stalls try the other one instead, if it still stalls it's not the ram. (Sometimes it'll give a Blue Screen of Death)
2) The next thing is the CPU fan has failed, (is failing). Take off the side of the case and look at the fan on the motherboard, is it turning slowly or not at all? If so just replace the heatsink and fan (usually around $20)
3) Hard drive is failing: It is possible that your hard drive is failing. There's a sure fire way of testing it, but the software costs $80 (It's called Spinrite 6.0) but if you don't want to spend that kind of money on diagnostics software, do this instead:
Open Computer by clicking the Start
, and then clicking Computer
Right-click the hard disk drive that you want to check, and then click Properties
Click the Tools
tab, and then, under Error-checking
, click Check Now
If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
To automatically repair problems with files and folders that the scan detects, select Automatically fix file system errors
. Otherwise, the disk check will simply report problems but not fix them.
To perform a thorough disk check, select Scan for and attempt recovery of bad sectors
. This scan attempts to find and repair physical errors on the hard disk itself, and it can take much longer to complete.
To check for both file errors and physical errors, select both Automatically fix file system errors
and Scan for and attempt recovery of bad sectors
Those are usually the major culprits. If you try all the above, and still are having problems, then the only thing else would be a faulty motherboard or CPU.