The HDD Diagnostic tool is a virus that imitates a system hard drive diagnostic tool such as disk defragmenter and confuses computer users to believe that HDD Diagnostic tool is a virus. It then attempts to convince computer users that it has found multiple problems with the PC and the user should buy the program to fix them. If you have this program, do not give the program payment information. It is a scam trying to steal your credit card data.
This virus infects into the system files and takes control over various hijack points on your computer making it very difficult for a average computer user to manually remove the virus. It also blocks out most anti-virus tools from removing it or even detecting it.