There's a nasty piece of malware going around right now, posing as a legitimate spyware removal tool that's spontaneously found a couple hundred threats.
First, a real malware scanner will not find threats as fast as this one appears to. It just wants to freak you out, so you say "Yes, please remove these threats!" and then you're screwed. If you see this, simply close the window that's popped up! Click the X at the top right of the window, or press Alt + F4.
If it's too late for any of that, you can attempt a system restore, but most of the time, the spyware will prevent this from happening.
You can try to download Malwarebyte's anti-malware. This malware may block your access to this site though. If it does, you can download it from another machine and transfer it to a CD or a thumb drive, etc.
One of the latest features of the malware is that it will remove the ability to run EXE files. If you open windows Explorer, go to tools, options, and to the "File Types" tab. You'll need to add a new extenesion for EXE, and associate it with "Application". You'll get an error that it already exists, and it will ask you if you want to change it. Click yes. Once this is done, you should be able to install Malwarebytes Anti-Malware.
Another thing you can do for EXE files that are being blocked by spyware is rename it to .COM instead of .EXE.