John Young wrote ...

I am trying to connect to Excel, not Access. The OS is Windows NT, and
the file was created using Excel 2003.
Interestingly, running the same program under Windows 2000 does not
generate the ISAM error.

The 'Could not find installable ISAM' error message can appear for all
sorts of reasons. The most obvious is getting the connection string
wrong e.g. change

Provider=Microsoft.Jet.OLEDB.4.0;
Data Source=C:\Tempo\db.xls;
Extended Properties='Excel 8.0;HDR=Yes' ' << correct

to

Provider=Microsoft.Jet.OLEDB.4.0;
Data Source=C:\Tempo\db.xls;
Extended Properties='Excel8.0;HDR=Yes' ' << error

If the same code works on another machine then you have to look at the
differences between the machines. If you are using a DSN rather than a
connection string, check both DSNs are the same.

The next obvious way of creating the aforementioned error is to change
something in the registry e.g. change

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Jet\4.0\ISAM Formats\Excel
8.0\Engine=onedaywhen

So there could be an issue with the registry. I can't think of any
applicable ini files.

Hopefully, looking for differences will highlight the problem before
you resort to rebuilding the machine.

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