Turbo C program inconsistent runtime problems

[Joe Duval - Entomology]

Hi, 
  I am using TC 2.0, DOS 3.3, 386 machine.
  I have a Turbo C program that compiles fine with minimal warnings about
variables not used (actually they are used inside of ifdefs).  However, when
it runs the program will crash, usually corrupting the screen horribly.  This
doesn't happen at the same point in the program all the time and sometimes
will not happen until you run the program two or three times.  The least
that happens during a run is that you may get a "Null pointer assignment" 
message when the program exits to DOS.

I did not write all of the code and the program has performed better in the
past.  I am using "Steven's Memory resident utilities/ Screen I/O & 
Programming" for windows and menus.  I added the user interface.

The last thing I did was to add some function prototypes and move some 
functions around to better organize the program.  This did involve splitting
up one file into two.  The program was behaving OK before these changes, but
not perfectly and is certainly worse than before. <:-)

I would like to get some suggestions on where to start looking for the
problems.  I haven't been able to pinpoint it to a specific point in the
program because it is inconsistent.  80% of the time the program just gets lots
of colorful, flashing, random characters on the screen and will lock up the
machine, but not at any one spot.  Where should I start?  What should I look
for?  Are there programs out there that will help me?  I have tried the 
integrated debugger that comes with C but as soon as the program crashes I get
some "system not ready error" and the machine needs to be rebooted.

There are probably some pointers out there that don't get malloc'd correctly
or start pointing to other things maybe.  This is a fairly large program and
I would like to jump into debugging it with some direction.

Thanks for reading
Send Help

-Joe


--
Joe Duval		duvalj at bionette.cgrb.orst.edu
Looking for 62-64 Chevy Nova body parts.  I've got a 63 Nova SS forsale.