Shadow-no sound on text message (please help!)

[Guest joto]

My shadow randomly stopped vibrating / making any sound when a text comes in. I did a hard reset and it worked....enabled and changed the MMSC settings with CeRegEdit and everything was working fine....a few hours later....no sound on text again. All i get is the blinking light and the screen turns on. It still rings / vibrates on calls so i dont think it is a hardware problem. Does anyone have any ideas?

Thanks!