I have a problem with my computer recently. It can not boot and this error appears: "invalid partition error". when I use windows vista's CD and try to repair it, it can not find operation system and drivers. I couldn't find any useful thing in drivers and utilities CD too. I thing this problem has been caused by a virus, I don't know how can I fix it.

Might look at using ranish to try to fix it. Ranish is on ultimate boot cd I think and others. Some norton products (ghost 10 I think) have partition tools on cd also. Until the partition is fixed vista dvd will not see any os installed. There are good tools on the vista dvd also but I'd start with ranish myself. I'd suspect other issues than a virus but it can do that. "Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10