Yesterday you also replied to your duplicate post created on 5/04/12 in the Windows 7 forum. Along with your thanks, you wrote:
"i have no idea what was the virus.but it kept telling me i have got a virus and do a scan which was called S.M.A.R.T scan, so i did what it said then all gone."
If you read, "Remove Smart HDD (Uninstall Guide)", you will find where it states:
"Smart HDD is a fake hard drive optimization and analysis program that displays false information so that it can scare you into thinking that there is something wrong with your computer's hard disks...
Once installed, Smart HDD will be configured to start automatically when you login to Windows. Once started, it will pretend to perform a S.M.A.R.T. Check routine that supposedly examines your hard drive for S.M.A.R.T. errors. When it has finished it will present you with a S.M.A.R.T. Repair screen where it will display a fake hard drives diagnostic report. This report will state that there are numerous issues with your computer's hard disks and then prompt you to repair these issues.: .. "
If this should happen again in the future, I would suggest FIRST looking at where the warning is coming from. If you don't see your A/V's logo (or another application YOU installed), do not proceed any further. If you have any doubts, you can always post here (with the name) and ask. Quite a few of the removal guides, found as a result of a Google search are "questionable", at best. It's why many of us have a safe browsing tool such as Web of Trust (WOT) installed.
Best of luck in the future..