Help, open/save file dialogue box won't open

[Stone Cold]

From any program, if I try to open a file (file/open), the file dialogue box doesn't appear. If I try to "save as" (file/save as), the file dialogue box doesn't open. The right-click menu in the browser also won't bring up the file dialogue box. Nothing I do will bring up this dialogue box. When I try, the edge to the window appears to flash, but nothing more happens. Everything else seems to work fine.

I'm using Windows 7, 64-bit. I've tried Google for the answer. But, no luck. Thanks in advance.