I've solved the problem:

It is a known bug by Microsoft and it was solved in Visual studio Servicepack 2.
Because i've ran this service pack under NT the error didn't occur there. And because i use the same VFP environment in W95 as in Winnt 40 i didn't have a problem in the development environment under Windows 95. But when i used the executable it uses the DLL's in the windows 95 directory which where not updated. I ran the service pack and the problem was solved.

Thanks anyway,