HELP needed with initgraph()

[Jackle]

I have a little problem with my Turbo C program.  It works fine on an
IBM PS/2 with MCGA, but when I try to run it on my IBM compatible with
a VGA card, it freezes during the execution of initgraph().  I checked
everything and discoverd that I can correct this problem by decreasing 
the size of one of my arrays.  The array itself doesn't take more than
6K of memory.  I'm using a 320x200x256 mode supported by svga256.bgi.
Any clues?
Also, I'm unable to execute the code directly from DOS.  If I try,
I get a blank screen and the program freezes just as above. 
Sounds familiar?

Thanks in advance for any help.
J.