keyence kv-40r problem, hardware problem? Options

[kolonelvonklink]

Hi

I'm using an old keyence KV40R for my sun blinds.

A few months ago it didn't work any more. A short power off and everything's OK

A few weeks ago a few inputs (which are all connected to ordinary switches) wend crazy. he blinds wend up up down up down down up.........
A short un- and reconnecting these and everything's OK

Yesterday same problem, same solution but after a few minuts all inputs wend crazy flickering almost always on, even the unconnected ones. The blinds wend up up down up down down up.........

Now it's on my desk and everything seems OK

What can cause this.
How do I prevent the unnecessary switching of outputs
Can a digital tv amplifier? in the neighbourhood 0.5m cause this?

thanks