I'm having the same issue with my newly built PC running Vista 64bit. I'm 100% sure that mine has nothing to do with keyclone. It randomly crashes on COD4 as well and did so before I even had Keyclone. Some days it never has an issue and some days it crashes every hour. With troubleshooting so far, I'm leaning toward blaming my Ram. I have a Gigabyte board and Gskill F2-8500CL5D-4GBPK 2x2GB DDR2 memory. I've seen enough complaints about the pairing of the Gigabyte boards with this memory that I'm ordering another brand of Ram. I'm also replacing my power supply with a more powerful one. Changing the Ram settings and voltages didn't correct the issue.