You didn't say which verion of Windows you're using...
Anyway, in case you haven't already tried, go here for <a href="http://web14.compaq.com/falco/sp_list.asp" target="_blank">Compaq's Presario drivers</a>. It looks like there is an old <a href="http://web14.compaq.com/falco/sp_syn.asp?detail=yes&recid=SP11386" target="_blank">ESS Solo 1938 Audio Driver for Windows 98 Ver. 4.05 </a> available for download.
You can also download the Compaq Diagnostics for Windows as well as your Service & Maintenance Manual and Quick Reference Guide.
It really sounds more like a BIOS/CMOS problem or conflict to me...the Diagnostics should be able to find it for you.
Also, when you get it all loaded up, how does it look in Device Manager? Any exclamation marks or errors listed?
Just a couple of suggestions...
Good Luck!