I was receiving the same error until I relocated my *.asm to the MPASM
     directory where MPLAB executable resides.  Since then, no problems.
     Hope that helps...


     Tim Crist



     >I've just started using MPLAB 3.22. I'm having problems with creating
     >and opening projects. Whenever I open a project (project file created
     >with 3.22), the primary file is not automatically opened for editing
     >and
     >I get a dialog box telling me "Error Opening HEX File".


     >Frank Richterkessing