Fatal Simulate Error due to Memory

My simulate has been suffering from a fatal error when attempting to run an assembly simulation of 9 small parts. Total element count is approximately 128,000 and I am allocating 3 GB of RAM but during the first pass it always fails with the following error:

"The design study terminated abnormally.
An error has occurred while requesting an additional
3.072 gigabytes of memory from the operating system.
To correct this problem, you may need to increase the amount
of swap space on your system.  You may also need to increase
the memory usage limits that are set for your system.
For large problems you can also try decreasing the
solram allocation setting.
At least 21.9693 gigabytes of memory are needed to run this design study."

I have run larger (greater number of elements) models in the past with an identical RAM allocation without error. SOLRAM has been increased after a previous error but that did not solve the issue. I don't quite understand why it won't work so any insight would be gratefully received! 

Nick