Hello jamccor,
As the first diagnostic I would suspect that your .scr (scrfile) settings as installed by default in the registry have been altered/corrupted for whatever reason. You can investigate the reason later. Would it be due to virus...?
But to correct the situation, I would propose you to use right-click (context-menu) on a good .scr file in your system under \windows. Do you get the choice "open" (default), install, config? If not, it confirms the diagnositc. If yes, you still have to make sure the settings are the correct ones.
Use any box with .scr properly behave and export the keys:
[HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\.scr]
and
[HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\scrfile]
As these are the areas where we tempt less to customize, you will properly be all right to import the .reg settings to your box.
If you are worried about it, you can post the settings in your box right now. I am sure members can spot the anomaly comparing them with their settings.
regards - tsuji