PIX 515 locks up after installing VPN Accelerator Plus add-on card

Hi!  I have a PIX 515 with unrestricted license.  It has both VPN-DES and VPN-3DES-AES enabled.  I use the VPN clients now with the PIX and want to setup some site-to-site locations.

I purchased a VPN Accelerator Card Plus (P/N: 74-3176-01 VAC+) and installed it recently.  After I restarted the PIX, everything came up flawlessly and the accelerator card showed up when a ran the 'sh ver' command.  All my internet traffic was working and everything seemed to be good to go.  After about 30 to 45 minutes, my PIX locked up and I could not get any traffic in or out.  I shut down the PIX and rebooted.  Again everything came up okay.  Then 45 minutes to an hour later it locked again and would not let any traffic either way.

This is my production PIX so I removed the VAC+ card and am running now okay as before.  Does anyone have any suggestions as to what I may be doing wrong or how I could go about solving this issue.  I am at a loss.  I can not find any installation instructions that say this is anything more than plug and play.

Thanks in advance for the help!