Aborts when shelling out of D3 version 7.3

I have a program written in VB which is called via the D3 "!" verb, and
which has been working fairly well until I tried to install it at a site
running 7.3.4. At that site, it aborts with an application error when it
calls a Crystal Reports OCX to print or export a report.

I've duplicated this behaviour on my own system by loading up 7.3.0. It's
interesting to note that the problem doesn't occur if the D3 service is
logged on using the local system account, whether "Allow service to interact
with desktop" is checked or not.

I know that RDTA have made some changes in the way that the ! verb works,
because under 7.3.0 the shelled process always seems to be able to interact
with the desktop, even when that option is unchecked. I suspect that it
might be something about these changes which is affecting my process.

The problem also occurs when I try to load the Crystal Reports application
itself. I get a C++ Runtime Library "Runtime Error". When the VB app runs,
this error is preceded by a "Memory could not be read" type of error.

I also notice that I get an "Out of memory" error if I try to invoke the VB
IDE from D3 7.3.0, though the IDE seems to recover.

Any ideas or common experiences?

TIA,
Luke