Problem with Windows XP log on/off sound, also Spider solitaire sounds.
Recently installed Skype, which I've since removed because sound didn't seem
to work, although all these worked/still work with MSN Messenger.

Since then all other sounds do work except for the Windows XP log on/off and
spider action sounds.

In the Control Panel, Sounds and Audio Devices panels it appears as if all
sounds are correctly selected. However, I cannot access all options and it
seems to me as if Realtek (I have Realtek sound system) suppresses certain
actions. On other PCs, not using Realtek, these options are available.
Any ideas / advice gratefully received.