Currently Being ModeratedFeb 5, 2013 4:02 PM (in response to Nick Stearns)
Most often the cause is some USB drive, I'd test without them attached, then one at a time.
Also, Open console in Applications>Utilities, check the system log for the date/time of the last problem & the Startup right after that for clues.
Currently Being ModeratedFeb 8, 2013 4:45 AM (in response to Nick Stearns)
As BDAqua suggested, I started the process of elimination by shutting down the externals and just leaving up one of the USB drives and using the computer until time to shut it off. After eliminating 2 of the 3 drives I figured it had to be the last one. That drive is a Seagate GoFlex Desk version that allows different bases with differing connectivity. I had previously used FW800 to connect but had switched to USB3 on the new computer. I went ahead and got a Thunderbolt to FW adaptor cable and switched this drive back to Firewire rather than USB3. So far so good.
Thanks for the help BDAqua!