My RFM used to do the same thing from time to time - green bleeding across the screen. Mine would do it from time to time, then got a bit worse, but still intermittent.

I managed to trace the fault back to a bad connection on one of the two connectors goinginto the PC - try reseating things at that end and see how you go.

IIRC the connector that was causing my fault wasn't actually the one that feeds the monitor, but the larger one that does everything else.

HTH