You shouldn't see any errors in the PostScript code generated by dvips,
but there may well be problems in a PostScript file included by \special.
(You can always tell which is the culprit by commenting out the \special
command.)
If you are sending the output to a printer rather than spooling software then
any PostScript error should cause a message to appear in the window.
Any further output will be flushed and printing cancelled.
So what can you do? For starters, get the
PostScript Language Reference Manual by Adobe Systems.
Debugging a PostScript program can be a frustrating experience.
Try downloading the error handler stored in errhandler.ps.
If the problem isn't obvious then use print and flush commands
to isolate just where the error is occurring.
The Ghostscript program mentioned in the ``Related Software'' help file
can also be useful.