I'm having the same problem on v.8. I also have more than one company file, and only have problems with one. I had the same problem a couple of years ago with the same company file, and had to restart from scratch.
When I try to turn over the fiscal year, the process gets part way through, and then just terminates. After that the file is unusable.
I found one bit on the MYOB website that might suggest that using a different font on reports other than arial may cause errors. So far this has not fixed my problem, but I am going to try again, as the file I have problems with has a downloaded font on some reports, whereas the one that works OK does not.
If anyone could suggest anything else, would be much appreciated.
Randy