It sounds like you may have something running which is preventing you from being able to run standard programs. What I normally do is use Rkill to stop the malware processes that start when the computer comes on. Then I run the Malwarebytes and SUPERAntiSpyware. Here are some DL links for the Rkill....LINK 1LINK 2LINK 3LINK 4
Save it to your desktop and then double click to launch it (With Vista you need to right click and select run as administrator). You should see a little black window open and then close. If you see that box then it worked. If you don't see the black box then delete the file and use another download link and repeat the steps.
Once it runs you should be able to run Malwarebytes
and then I would run SUPERAntiSpyware