|Malware (viruses, trojans, etc.) sometimes prevents you from running programs you can normally run.|
Try downloading, installing, and running the free version of Malwarebytes.
See response 1:
Note that sometimes you can only install Malwarebytes in Safe mode - in that case, loading Safe mode with networking is required in order for it to be able to update itself.
Ignore the part about loading your latest System Restore restore point unless you did what the guy in that Topic said he did in the first post - loaded a previous restore point.