Date: Mon, 7 Aug 1995 07:51:53 +0300 (IDT)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Mats Grahm <pt93mg AT pt DOT hk-r DOT se>
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Re: grx mouse trouble


On 6 Aug 1995, Mats Grahm wrote:

> > : But no luck. MouseDetect() returns true, and MouseEventMode(), MouseGetEvent()
> > : and some other functions does not complain, although I'm not sure they do what
> > : they should. But Some functions, like MouseInit() and MouseWarp() terminates
> > : the program with the message "Internal error: invalid driver called".

Perhaps you will find the following excerpt from the DJGPP FAQ list 
(available as faq102.zip from the same place you got DJGPP) of some use:

10.7  Q: When I use 0xD0000000 as the starting address to access the video
         RAM in graphics mode, nothing appears on the screen.  What am I
         doing wrong?
      Q: When I try to use graphics under VCPI, I get this message:

           ``Internal error: Invalid driver called''

      A: You have to call GrSetMode() function to initialize the
         0xD0000000 area manager which takes care of the mapping described
         above.  Before GrSetMode() is called, all function pointers which
         normally select the video frame buffer access functions (and
         these are different for every supported kind of SVGA), point to
         an internal function which just prints the above error message.
         Note that the call to GrSetMode() has to be *successful* to
         correctly initialize those function pointers.

Did you call GrSetMode()?