cimplicity error

We have PLC5-80e plc and cimplicity. There is look like loss of communication and The whole screens on HMI (Cimplicity) get black-out,we have to waiting at a moment and the cimplicity will be start up with it self. in alaram we get message :"comm error or dynamic disable". We use ethernet for communication between plc and computers.
Give me some solution for reducing our downtime.

Regards

My first thought would be to replace the computer that is running Cimplicity. Sounds like a power supply or motherboard problem.

Thanks for your replay RussB

Actually i have changed the PC but the problem still coming up, for your information, i used first scan bit on my program and i got that bit sudendly ON, i dont know why? i have changed the PS PLC, CPU, PS Cable, check all wiring, but the results still same.
i hope any idea what other way must be i do..

Regards