Norton 360 won't start, and other problems

Hi. I think I have a virus after stupidly opening a bad email attachment because sometimes google searches take me to a different site instead of the one it’s supposed to, and Norton 360 doesn’t start. (nothing happens when I double-click it’s icon and it no longer appears in the task bar.) I tried it in safe mode and it says it doesn’t run in safe mode, and I tried the downloadable Norton Security Scan, but it says it’s not able to retrieve the most recent protection update from the internet and has no definitions available to run a scan. I tried CA’s online scanner and it said I have something called Pigeon GM in c:\windows\winlogon.dll but didn’t give any advice except to buy their software. Any help would be appreciated.