No system sounds in Vista Business

Hello all..this is a problem I just noticed and it's stumping me...

Recently (and I don't know how recent being that I just noticed it) but my
PC won't play system sounds at all...and sites like youtube don't work either.

I can go to the Vista/windows/media folder and play the sounds individually
through WMP11, but the sound will not play when they are 'supposed' to during
normal computer operations. For example...I can delete something, yet won't
hear the recyle bin sound, my computer doesn't play the logon/logoff sounds,
etc...

I've tried to do a system restore, but it won't go back far enough to
correct the problem. I can't 'repair' the install since Vista technically
isn't 'broken' by it's own standards...

I've tried to rack my brain as to what I've installed recently that could've
caused this...what comes to mind are....

Tversity (XBOX 360 streaming program, which i've since removed)
K-Lite Mega Codec Pack
iTunes (since removed)

manually playing sounds works. playing sounds in video files works, playing
mp3s works, playing wavs work (when played through WMP), but the system
sounds don't work at all...

I've searched all through google and such and cannot find anything to help
me out...

I really dont' want to reinstall windows vista, especially since you're only
allowed to install it 'once'...but, if I have to, I have to...

Any suggestions would be greatly appreciated... thanks