Your System is Out of Memory - Citrix platform & Primavera P6 ver. 7.0 SP1

We are having this issue with multiple project files with over 65000 activities, and when we try to calculate (F9) all of them together, we receive a message which says:

"Your system is out of memory, Please close other running applications and try this operation again".

This happens in the middle of calculation. First we want to make sure that our files are not corrupted due to this message.

We tried a workaround and reduced the number of activities in a single project file by breaking it down to more project files, and oppened all of them together to do do calculation, but still we have the same error message.

Our P6 database is Oracle and we connect remotely via Citrix 12.0.0.6410.

Thanks in advance for your help.