cubase 8 pro hangs after four measures

Hi everyone,
Just finished installing my Cubase 8 64 bit on my new dell T1700 workstation. I removed firewire card from my old PC and installed it in on PCI slot given in this workstation. I am using Focusrite saffire pro 40. The problem is that Cubase 8 hangs after playing for 4-5 measures of 4 tracks of audio playback, and hangs after first measure if I record audio. The message says too many audio tracks.
Is this PCI card slot issue on my workstation (should I try to connect saffire to the thunderbolt port?)
or some compatibility with Nvidia K620 graphic card
or some internal setting in windows 7 which might solve this problem.

Regards
Sandeep

I did some research, intel C226 has a PCI slot but does not support it ??? I have ordered a thunderbolt to firewire adaptor (Apple). lets see if the software works when I connect saffire pro 40 via thunderbolt.

update: Its working perfectly via thunderbolt. saffire pro 40( firewire 400 to 800) to thunderbolt adapter (firewire 800 to thunderbolt).
So there is a PCI slot on Dell T1700 ( intel C226 chipset) but its not supported. Whatever it means.