The error message “Unable to create the display plug-in MPForum.Forum.1” has been plaguing me on my laptop. Whenever I launch the MPLAB 8.92 programming environment it immediately crashes. I spent hours last year trying to fix it to no avail, and I spent almost all of yesterday too. The Microchip forums have a number of posts on the subject but none of them offered a solution for me.
Finally, I have found a solution! The problem is caused by DEP (Data Execution Prevention). The MPForum.dll has a bug that triggers DEP into terminating the process. To work around this, simply disable DEP for mplab.exe. This is done in the System control panel, search Google for exact details.