Windows Vista Loss of Sound [When activating new user account]

Has anyone come across a siyuation where the sound card is working fine but as soon as a new user account is added, virtually all programs lose wondows sounds (to the extent you can't even play a sample sound in the sounds folder of the Control Panel). The only exception seems t be Skype which operates normwally.

I have done so many system restores to get it back to the sound functioning only to have it fall out on me again as soon as I activate a new user account. It seems to work fine with a single user