Okay, try this. However, I won't wish to be hold responsible for any incorrect changes made to registry in this phase. Follow these instructions as you wish:
1. Click Start -> All Programs -> Accessories.
2. Right-Hand click on Command Promt run this as an administrator.
3. A warning box may or may not appear asking you if you wish to run in administrative mode -> Continue.
4. Run the following command (Type this exactly):
sfc /scannow
5. The above is written (sfc *space* /scannow) -> Hit return.
6. You should see a return value - "Beginning System Scan..."
7. After scan has completed (can take several minutes) the registry will check all protected .Net files.
8. Incorrect versions within the file will be replaced.
9. Any errors will be reported to you and if they have been fixed or not.
If the errors cannot be fixed, you will have to search a Microsoft knowledge base (or Google) for answers.
I really hope this helps.
This may help.
