SCL Source and FCxx different time stamps

Hi,
I'm fairly sure that the boffins in here have already solved this several times but I cant find it...

I have a program from an S7-400 that I'm hoping to debug (offline)
I have V5.5 +SP4 installed on my XP VM.

My debugging has led me too an FC that I cannot open, every time i try I get:

"Block FCxx and the source file @SCLFileFromCFC_SFC_1 have different time stamps"

A completely different FC block then proceeds to open...

No matter what FC I try to open I am having the same issue...

Any Ideas?

I haven't mentioned how infuriating I find Siemens S7, I'll leave that for another time!!

Your over your head.
Sounds like a PCS7 project.
You really need PCS7 and the CFC source

what if you delete or rename files from source folder on step project.
Then FC blocks at least should open on STL format.