I think that 2gb is the maximum size for a pst file - round about that amount thigs go decidedly wrong - I seem to remember something very similar when I had 98. I also think that once it has reached that size there is very little you can do to make it smaller - even deleting stuff out of it maintains its size.

If you rename the pst file and start again you may be ok and I think there is another tool (apart from the windows one) that may help you repair it. Sorry not to be more specific but it's a few years ago since I came across this

There is an article here that might help