Compiler 4.047 to Compiler 4.121

[Fusillade]

I have a program that was written in 2008 and was compiled with v4.047. The program runs fine and has been for 4 years; however, a customer would like me to make a small data change. As it turns out, my CCS maintenance expired 3 weeks ago (I updated for a new project in 2011) and my boss isn't eager to update my maintenance for a simple firmware change. This is why I have to resolve the problem with the latest version of compiler I have which is 4.121.

Problem:

I made a duplicate copy of the project and compiled it using v4.121 without making any changes to the code. It compiles with no errors; however, it does not function correctly.

I'm currently doing a list comparison. So far, I've had to add the following fuse declarations in my duplicate code which I did not have to declare previously:

#FUSES NOFCMEN
#FUSES NOLPT1OSC

Has anyone been down this path before?

Any help to point me in the right direction would be appreciated as I would hate to spend weeks debugging old firmware so I can make a 5 minute change.

In the meantime, I'll continue to do a list comparison and search these forums for tips.

Thanks
_________________
New:

Compiler Version: 5.078
IDE Version: MPLAB X V4.15
Devices: PIC18LF****

Old:

Compiler Version: 4.121
IDE Version: MPLAB IDE V8.63
Devices: PIC18LF****

[PCM programmer]