Well, thanks everyone for helping. I've solved the problem. I had
a *old* GDS32.DLL installed somewhere in the Win path, which my app
was picking up. I removed all FBCLIENT.DLL and GDS32.DLL files from
the machine, cleaned up the paths, copied over my .EXE and GDS32.DLL
(renamed from FB 1.5's FBCLIENT.DLL) to a new folder and all is well.

Now, if there was just a way to compile GDS32.DLL into my .EXE :)

Hmmm...anyone use Thinstall? (www.thinstall.com)