Windows 7 SP1 problem with permission

Hello everybody,

I have a hp dv73060 laptop and few hours ago and I installed windows 7 SP1 to update my windows 7 and now that it is installed my laptop is completely useless. When I try to open any files, I get this error "Windows cannot access the specified device, path, or file. You may not have the appropriate permission to access the item"

Nothing will open! I tried to uninstalled SP1 but it won't let me do that. I tried to change the ownership but it says that I don't have permission to do so. I tried to go in safe mode but I get the same problem. My PC is totally useless. I don't know what to do now. Any suggestion? Thank you.

Chris.