cannot execute as child of BASIC - any ideas?

[Nick]

Until now I have used a small piece of third party
software in Windows 3.1, W95, W98 and W2000 without any
problems.
Attempting to use it in Windows XP Home I sometimes get
the following message, and the programme fails to
run: "cannot execute as child of BASIC"

The software writer says its a Windows problem, not his
software (which he tells me is a compiled BASICA
executable program.) He is probably right, as it seems to
depend on what other software is loaded onto Windows. For
example, it failed to work on a brand new OEM version of
XP Home. After installing a few Office products, it worked
fine for some months. After installing one or two other
programmes recently the error message came back, and I
could only get it to work again by going back to the pre-
install Restore Point. Its working fine now, but I'm very
wary of installing any new programmes in case it messes up
the registry again, or whatever causes the above message.
Any pointers (of a non-technical nature, prefarably!)
would be much appreciated. All the usual web searches and
knowledgebase searches have revealed nothing except except
for an issue around Compaq PC using Win98, and my PC is
not a Compaq.

Nick
Derby England