I'm not the best one to help at all, but when all else fails, I reset the computer to a previous date back to whenever I didn't have the problem. Often works to get rid of the chink (virus, whatever) that's blocking you. Do you know how to do that?
In case you don't: Click Start, then click on All Programs, then Accessories, then System Tools. Choose System Restore and choose Restore to earlier date. A calendar will come up with some of the dates highlighted. You can go back even further than the current calendar if needed. Just choose one of the highlighted dates. You may lose some things you did between that date and current date, but you won't lose your saved things or programs. It sounds more complicated than it is - you just have to move your mouse over the choices. Can't figure out why computers make you do 6 different things just to complete one thing, but that's how it is.
May or may not solve your particular problem, but worth a try.