Reasons could be -
1. VC++ 6.0 is corrupt - in which case you need to reinstall it
2. Windows became corrupt - you need to repair Windows 7
3. Hardware error like faulty memory - you need to replace RAM in the computer
Is there any other software that is giving similar error? If not then it is 1.
Create a memtest CD and run memtest for atleast an hour (more if possible). If it shows error then it is 3. (http://www.memtest.org/#downiso)
Else it is 2.