STAAD Error No. 41: Not enough memory

Hi,

STAAD v8i doesn't run analysis without MEMORY-command in input file. Output file then only contents of two lines:

1. STAAD SPACE
ERROR NOT ENOUGH MEMORY TO START ANALYSIS. ( 41 )

But available memory should be enough. We tested with two computers (each more than4.3 GB free disk space) and evaluated the limit MEMORY 67 (with each compter). That means: MEMORY less then 68 works, MEMORY more then 67 fails. Can anybody explain that?

Thanks for a reply.
Best regards,
Christian.