Unable to Preview Model in Smokeview

[ptb]

Hi,

My computer has recently been upgraded to Windows 7 Enterprise, 32bit.  When I try to use the Preview feature in Pyrosim, it doesn''t load past the first line (see screenshot), and proceeds to use 50% of the CPU running fds5.exe (my comp has 4GB ram, quick processors etc).  The model is not abnormal, nor does it work for previous models which I know work.   

Any ideas?

Thanks.