540c crashes MCL 2.0

[rghst8@vms.cis.pitt.edu]

I have just purchased a PB540c and upon trying to run my MCL version 2.0, 
everytime I execute a floating point number calculation, such as (+ 2 1.5),
I get a message "Stacks reset due to overflow". Also, everytime I try to access 
the online documentation under the tools menu, the application crashes and 
gives a message "Application has quit unexpectedly, an error of type 10
has occurred". An error of type 10 is "line 1111 trap error", whatever that
means. Is this problem because MCL 2.0 is not compatible with system 7.5?
MCL 2.0 runs perfectly fine with my PB180 running system 7.1.2.
Also, does the fact that a 5xx PB doesn't have an FPU cause the stacks
overflow error message above?

Thanks