unable to open .exe programs

[maddierose]

hey guys, for a while now, I have been having a strange problem which im sure is virus related. When I log in, I get windows popups, due to .exe programs being unable to run. They come up with different headings, yet the actual notifications inside are all the same. The headings are:
HPAdvisor.exe - Configuration parser error
HPWAMain.exe - Configuration parser error

When I try to open The Sims 3 which I have tried to install from the original disk which used to work fine I get this:
Sims3Launcher.exe - Configuration parser error

I tried to install Facebook Messenger last night, when I try to run it I get:
FacebookMessenger.exe - configuration parser error

Inside all of those notifications is this same message:
C:\Windows\Microsoft.NET\Framework\v2.0.50727\config\machine.config
Parser returned error 0xC00CE556

For antivirus I use Avira Free Antivirus, I have done a full scan which has detected nothing. But I am unable to update it, when I click "Start Update" I get a notification saying
The following error occured when trying to start the update:
Access denied..

I am hopeless with this kind of stuff, how can I get my computer back to normal? Thank you

 

[Martell1977]

Here is a link to how Microsoft recommends fixing that error:

http://answers.microsoft.com/en-us/windows/forum/windows_vista-windows_install/parser-error-0xc00ce556/c8a0a7cd-a5cc-46c3-9e76-96306143d36b

Looks like its some corrupted files. Once sorted out I would run Checkdisc to make sure the HDD is good, if all is well, maybe run Housecall by Trendmicro to make sure the system is clean:

http://housecall.trendmicro.com/