Hi,
The message you got is a message from DirectX. So check if your DirectX is well installed.
It should but just to be sure.
It seems Z26 want a DirectX3 , it is quiet old. But it should work on newer version.
The problem could come from a conflig with Mamewah. I don' t know if it uses Direct X too but i think. May be MameWah does not free DirectX correctly before running the emulator.
you could do a quick test with my Front End : AtomicFE , and check if you have the same probleme May be not. I use Z26 too (but not the last version) , and i don't have that error.
If you try Atomic, it you got the error , go on the options Tab and Uncheck the checkbox "Hide Emulator loading".
Let me know.
When you run Z26 without the FrontEnd , do you have this error?