Yeah, it's W7 first service pack, I think the XP service packs are up there with the Rocky films.
My Desktop system is really rather plain, I use Avast, the free version and W7's own firewall. A good number of people have had this problem but it seems it's still in it's early days as there is nothing by way of a solution out there. I only use Windows for what I can't do in Ubuntu, and the occasional gaming.
If any want to be ultra sensitive about upgrading to SP1, they may also want to make sure their BIOS is updated, as well as what Madders suggests. This said, because of the diversity of systems out there, I suppose some will go belly-up as did mine.

Just be a nutter... life becomes much more exciting, and people won't expect anything more of you...