Precision 5510 hangs on reboot

I have the thunderbolt dock.  When the machine is connected to the dock with the lid closed and I reboot the machine, it hangs at the Dell Logo and the front LED blinks  7 times white and 2 time amber.  It will continue to blink in this pattern indefinitely until I open the lid, power off the machine and power it back on (with the lid open).  If I try to power it on with the lid closed it will hang again in the same manner.

It will often then boot into the online diagnostics and run tests.  I've run both the default express diagnostic tests and the extended complete tests, but it never finds any problem.

The documentation that I've found indicates that 2 amber lights means that the laptop can not find the memory.  However the documentation does not mention anything about the 7 white blinks that happen between the amber blinks so I'm not sure that it is really telling me it thinks it has a problem with the memory.

When not traveling, I tend to leave my laptop  powered on 24-7 and remote into it from home to do support work off-hours.  If  our IT dept happens to push an update  that requires a reboot, this means I've got to drive into to work to physically reset everything so the machine will boot.  I would really love to fix this problem.

BIOS version 01.01.19, 1/25/2016