Hello and Welcome
Goto ->
http://vil.nai.com/vil/averttools.asp
Under the utilities download
Fixswen.inf, once downloaded Right-click on it and choose install.
See if that lets you run exe files again, if so post up a hijackthis log.
Run an online scan at
Trend Micro or
RAV Antivirus.
Please select the autoclean option when using Trend Micro. Please let me the know the names of any viri that are found. If these don't work report back here.