Thanks for your reply Rick.
I have also upgraded to MP7.6 on the PC and I have tried opening the file first thing and used "Save As" but CS3 immediately crashes. I too am holding my breath on new files waiting for this to happen on the next file. I have turned off the PDF Compatability as well as the Compression option and also removed Version Cue.
I have noted that a lot of people on the Adobe Forum are having Save file problems but Adobe doesn't seem to be doing anything about it from 6 months ago.
I am a Freehand User as well and never experienced this problem.
Does anybody from Adobe read this site - if so, Do Something NOW!!
I've recently moved up to CS3 with MP 7.6 on a Mac (10.5.2) and have occasionally encountered the same problem. I can't say whether it's related to MAPublisher or not. Typically I do a save as each day with the new date in the file name so if I screw up I can go back day by day. What I have found to work for this problem is to open the file first thing in the morning and before doing anything, immediately Save as with the new date in the name. For the remainder of the day the file will save just fine, although I hold my breath a lot when hitting save later on. Additionally I do not check the PDF compatibility box so as to reduce save time and file size.