The problem you described,
.snip
 
>Yesterday, I downloaded from HP's FTP site, the latest PCAPI ODBC
>software.  I ran the self extracting file OK and then ran the Microsoft
>ODBC Setup program that came with it (as I had done the first time with
>the older version of the PCAPI successfully back in December).  The
>program let me select the ALLBASE/SQL interface, but it returned and
>said that the software was not installed and to run the setup progam
>again (which I did with the same result).
 
is a known problem, and was first reported to both Microsoft and HP in December
of 1994.  It usually shows up after you have installed a newer release of user
software like Excel.
 
This is the meaningful text from the RC call:
 
During setup, right after you have highlighted
HP ALLBASE/SQL as the driver you want to install and
clicked ok, you will get the following message:
 
   Microsoft ODBC has not been installed, run Setup
   to install ODBC.
 
Workaround:
-----------
 
Check on your PC for the occurence of the file
W32SYS.DLL. This file comes with Win32s. Rename all
instances of this file, then run setup to install
PC API ODBC. When setup has succeded, you may rename
these files back to W32SYS.DLL.
 
Peggy Lacy
HP Database Expert Center