No Sound Card Installed?

[wilder]

I upgraded to wmp 7.01 2 days ago and since then have no (legible) sound through my speakers.
I have w98. I have up-dated drivers, done file checker and everything else I can think of. Even re-installed w98 from disk. Error messages I have received include (depending on what program I try to run):
'No sound card installed'
'Sound in use by another caller such as at the priority level'
'driver not digitally signed (essolo.vxd)'
'WMP error:the device is not ready'
I have switched output jacks and no difference.
C:\CP\Sounds= no sample sounds will play

I am at a loss as to what to try next...

[wilder]

Also my sound volume control icon keeps appearing-disappearing from the toolbars. I can't open the sound volume control from windows either. soundvolume32.exe will not open.

[wilder]

Solved the problem.
I uninstalled/re-installed WMP and all's well. Apparently was a bad copy of WMP. Had corrupted files from IE before...