"Access violation" when trying to simulate

[george__]

I am running some simulations, I made a copy of a file and changed one component (the optimizer used). The simulation worked for some files, but for larger systems, I received the following error when trying to simulate:

"Access violation at address 00B8877F in module 'Pvsyst6.exe'.

Read of address 000000089

DateSim = 05/01/90 10:00 "

Is there any way to resolve this?

Thank you,

George