audio codecs control panel is screwey

This has been driving me crazy, perhaps someone in this group can help?

Using XPsp2: I hope somone can help me with the following cluster of related
problems:

a) When I install a new codec (vorbis.acm for example), it does not appear in
the Control Panel / Sounds .. / Hardware / Audio Codecs / Properties listing.
The codec does appear in the HKLM/.../Drivers32 registry.

b) The display in the audio Codecs listing is erratic:

1) When I click on properties for one of the codecs listed, then return to
the list, some codecs appear or disappear seemingly at random.

2) Sometimes the codec name in the list does not match the name that shows on
the property page; for example, the list item might be "AC3acm" but the
property page will say "iviMP3".

3) If i close and reopen the Audio Codecs listing, sometimes the codecs at
the bottom will appear twice.

I did a websearch for this problem, and found that a similar problem can be
caused by blank entries in the HKLM/..../Drivers32 and /Drivers.desc Keys. I
checked there, and there are no blank entries.

How can i solve this (i truly don't want to re-install, it's a heavily loaded
machine). Thanks! - Jong