You can try out two things,
1. Clean Boot
2. Recover older Registry
First try out "Clean Boot" here is an excellent article about Clean Boot.
"Clean Boot What it is and why you need it
If this does not fix your problem you can try to restore your old Registry.
Follow these steps to restore your Registry.
1. Boot to DOS mode (hold Ctrl key as you boot for the Startup Menu)
2. Select "Command Prompt Only" Enter
3. Type SCANREG /Restore
This will offer 5 choices, one for each of the last five separate days you
Select the one when the problem started. And restart.