This is becoming a PITA now. Has anyone else had this error happen to them?

"hl2.exe" has stopped working (not exact but you get the drift). I'm not sure how much it affects the game, but frequesntly I see the error box when I log off.

Any ideas of how to fix this or civil remarks on what to do or pointing the way to a techie that would know? (I'm saving Valve as a last resort)

All input appreciated in advance.

DED