error message programme damaged

I used to have version 2.61 but when I downloaded the new version and installed it, it has come up with an error that reads This program has been damaged, possibly by a bad sector of the hard drive or a virus. Please reinstall it. I do not have a virus as I have checked that, I have a good virus detector programme (VisNetic) and I have also run a scandisk which shows no bad sectors. I have also reinstalled the programme but to no avail. The help file works and the autoupdater window opens but not that actual programme itself. That won't run at all. I am at a loss as to what to do, any ideas? Does anyone know how to solve this problem? The previous version 2.61 worked really well and I had no problems with that. I am running windows 98 SE. Has anyone else had this error message. It is so annoying that I can't get 3.0 to run and I know for sure that I don't have a virus or a bad sector. This programme spyware blaster is really cool