I have been getting a small dialog box in the center of
screen with a message that says:

This program has performed an illegal operation and will
be shut down.

If the problem persists, contact the program vendor.

This same message seems to appear with different DIALOG
BOX names.  Example:  Navapw32, Wnmsgupdt.

When you click on the "Details Button" it reads NAVAPW32
caused an invalid page fault in module KERNEL.DLL at
017f:bff7b992.

I thought this was a problem with my internet software but
seem to think that it is system problem.  Sometimes the
dialog box can be closed and other times you can not.  
When this happens it locks up the computer to where it can
not be shut down properly.  The only way that I have found
to shut the computer down when this happens is to shut the
power off.

Is there a corrupt file somewhere?  If so, How can it be
corrected?

Please help.