[AccessD] API calls crashing

I am totally at a loss on this.
 
My big Access 97 app (I know, I know, but it works) is crashing on one machine,
a machine it has run on for years. I've tracked it down to API calls. Any time
it calls a Kernel32 API it just exits - no message, no nothing, just closes. Now
it's perfectly possible that central ICT here have installed or updated
something overnight which has interfered, in fact I can only think that must
have happened. Question is, what can I do about it?
 
This is a typical api call which crashes out:
 

Private Declare Function apiGetComputerName Lib "Kernel32" Alias _
"GetComputerNameA" (ByVal lpBuffer As String, nSize As Long) As Long

 

I know I could use Environ to get the computer name but that's not the point.
There are lots of similar calls and they're all failing.

Help please.

Andy