Low memory error after last WinXP update (Clipper app)

After the last update provided for Windows XP a client started to complain that his application (developed in Clipper and growing with the company since 1988) is running out of memory and refusing to operate. This did not occur before this last Windows update. He reversed the update on some terminals and the system is working flawlessly again on these. Obviously not the ideal situation…

Can anybody cast a beam of light on what could possibly be going on in this matter? And on how this problem could be solved, or even circumvented?

Any contributions will be thankfully received.