It sounds like the PC power supply is susceptible to power supply bumps, You could try a MOV suppressor on the input to the gecko power supply, and also one on the input to the PC, alot of the power bars have these built in.
Is the Gecko power supply common at ground potential?
Also you can fit a RC network suppressor on the input to the PC, there are a few manufacturers that make these typically used on CNC power supplies.
Al
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.