Strange legacy software problem - can anyone help?

I've run into a strange legacy software problem. Anyone got any ideas?

My system is dual boot with 98SE on C: and XP on D:

I use an old 1980’s MS-DOS TSR for which there is not a good modern
replacement (it’s called Addresselope, and it addresses envelopes on a
laser printer in an easy, straightforward fashion; no earth-shattering
task, but one that’s simply missing from the scene never the less).
Addresselope works under both 98 and XP in a DOS window (but read on).

This weekend I replaced the motherboard in my system, moving from an
Asus P4T-E (850 chipset) to an Asus P4T533 (850e chipset). I did not do
anything to either operating system or the hard drive. All cards in the
system are the same and the motherboards, while different in some
regards, are overall quite similar and use the same Intel chipset
drivers. Both 98 and XP took their time “detecting new hardware”, but
both seem fine with the swap, overall, without a full reinstallation.

However, as mentioned, Addresselope was originally a TSR (although I use
it now “stand alone” in a DOS box), and it was activated with the key
combination ALT-INSERT. So I run the command prompt program to get a
command prompt windows, type “Addresselope” at the prompt, hit
Alt-Insert, do my envelope and exit, closing the command prompt window.

Well, when I tried to use Addresselope tonight under XP, it would not
activate. It was not “getting” the ALT-INSERT combination. The
motherboard is the “only” thing that’s changed, and no BIOS setting
(including turning off legacy keyboard emulation) would fix the problem.
Addresselope simply would not “Pop-Up” under XP. The Window just sits
there.

So I figured that there is some issue in the Keyboard controller or the
ROM or KBC BIOS that won’t pass the ALT-INSERT on the P4T533
motherboard. Bummer.

But then I booted Windows 98 on the same computer and tried Addresselope
under Windows 98 AND IT WORKED JUST FINE.

????

Now I didn’t do anything to Windows XP, where Addresselope worked
previously with the P4T-E. And there isn’t a problem in the keyboard
controller or the ROM or keyboard controller BIOS of the new
motherboard, or it would not work under 98. So why isn’t it working
under XP and, more to the point, is there anything that I can do about it?

I tried to run Command.COM from Windows 98 under XP, but it pops up and
then disappears instantly, not allowing me to leave it open as a command
window. Turns out that it's quitting becuase of "incorrect Windows
version". Anyone know a way to block version detection? Setting the XP
compatability attributes for the program to 98/ME does NOT allow 98SE's
command.com to run under XP, but a one or two-byte patch would kill it's
version detection (if I knew which byte to change to what), and I'd love
to know if using 98SE's command.com under XP would fix the problem with
Addresselope.

Anyway, I’d like to get Addresselope working again (without surgery on
Addresselope itself). It worked under the very same XP (literally the
same, on the same drive) with the P4T-E.

Anyone have any ideas?

Barry Watzman