About that link: http://pcsupport.about.com/gi/o.htm?zi=1/XJ&zTi=1&sdn=pcsupport&cdn=compute&tm=43&f=00&tt=3&bt=9&bts=9&zu=http%3A//www.hgst.com/support/downloads%23DFT
Appears to be email spoofing.
Really? I already tried the program in that link. (doesn't seem to work) I already deleted it. Should I change my email password too?
Link provided above should display a warning about email spoofing, and not the link to the hard drive diagnostics and PDF file that essexboy intended to give you. You shouldn't have found it necessary to enter your email address or password to get the diagnostic file at the link. but some sites do require you to register first. It should have been a point-and-click operation, with the end result you got the diagnostic file you needed.
If that's not what happened, then suggest changing maybe your email password and monitoring it for a bit.