The solution is to add something else in your checkoff list.
You need to verify the following:
- memory test
- CPU test
- USB flash test
- HDD test
Also, did you do MBD5 checksum?
An MD5 checksum is a 32-character hexadecimal number that is computed on a file. If two files have the same MD5 checksum value, then there is a high probability that the two files are the same. After downloading an Altera software installation package, you can compute the MD5 checksum on the installation file.
As notated, time becomes and issue. After spending hours on a problem, it is time to do something else.
My suggestion: get another hard drive, remove some RAM . Use the built in VGA and install a simple OS like Ubuntu or Knoppix
http://www.knoppix.org/You should be able to do Knoppix on the first try. If not,you got bad hardware.