Hi,
The SCR file type is primarily associated with 'Script'. In November 2007 the SCR file extension started to be used to transmit a Trojan. As a script or a screen saver this file can execute other files which carry the Trojan. The SCR file may be embedded within a ZIP file which could also contain a file with a double extension. I would suggest you to try the following methods and check if it helps.
Method 1:
Run Microsoft Safety Scanner and check if it helps.
Microsoft Safety Scanner: http://www.microsoft.com/security/scanner/en-us/default.aspx
Note: The Microsoft Safety Scanner expires 10 days after being downloaded. During this 10 days, it will remove all the virus infected files and folders. I suggest you to create a backup of your data and then Install Microsoft Safety Scanner.
Method 2:
Boot to safe mode and check if the issue persists. If the issue does not persists in safe mode, then place the computer in clean boot state and check if it helps.
Step 1: Boot to safe mode in Windows 7:
http://windows.microsoft.com/en-US/windows7/Start-your-computer-in-safe-mode
Step 2: How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7:
http://support.microsoft.com/kb/929135
Note: Once you are done with the troubleshooting, try the steps provided in Step 7 to reset the computer to start as usual.
Hope the information is helpful.