I came across this whilst looking for something else!
as a follow-up:
Pausing the communication between PFE applications and the SX100 will dramatically reduce the occurence of Vaccum logic 'lock-up'. I typically have Stage.exe and probewin.exe running, so I click the Pause button in the bottom right of the log windows for both applications.
On occasion I have also seen a Vacuum logic lock-up with no PS applications running. This would typically be if the gun valve was left in position 1, e.g. for several hrs, when position three was being requested (damn that non-automated valve).
A 'slightly' less aggressive reset (than turning off the electronics) can be achieved by using a Telnet connection to the PowerPC to force a reboot. The source will still be turned off, but the restart takes a little less time than a full reset.