It's simply that the object space is wrapping (for want of a better 
word) past the 2gb mark and thus oops > 2gb are seen as -ve by the 
stupid code that declares ops as int.
It is plausible that the changes Ian recently made to help with 
64bitness etc will fix this and if not then it is simply a matter of 
programming work.
I got bitten by this a few weeks ago but since I've been moving and
somewhat short of time, internet access and patience, I didn't do 
anything much about it.

tim