Open a command prompt and paste the contents of the code box below to simplify the check disk process hit enter for vista/7 users run this command from elevated command prompt.
CMD /C ECHO Y|CHKDSK C: /r | SHUTDOWN /R /T 30
This will boot your machine into A checkdisk it will take some time so allow it to finish.
After the checkdisk...........
Download the All in one Repair Tool Run the program vista/win 7 users please right click and run as admin. Go to step 4 and create a backup of your registry this tool involves changing registry keys and it is just a good idea to bak it up.Now go to the start repairs tab and run it with the following boxes checked.When running this tool disable your antivirus.
Reset Registry Permissions
Reset File Permissions
Register System Files
Repair WMI
Repair Internet Explorer
Repair MDAV/MS Jet
Repair Hosts Files
Remove Policies Set By Infections
Repair Winsock & Dns Cache
Repair Proxy Settings
Repair Windows Updates
Set Windows Services To DEfault Startup
Repair MSI (Windows Installer)
Reboot the machine after then check updates and tell me if the machine is running any better.