Welcome to the world of Windows ME. To make sure that it is not the OS, try putting your Soundcard in another PC, Non-ME, if it works, then you may have to delete all Creative drivers on the system and reinsert the card. If it works after this, good for you, if not try reinstalling Windows ME or getting another OS. ME is by far, the most instable Microsoft Product ever produced. Only Microsoft BOB beats it in general all around poor preformance.
If it works for you then don't fix it.