How do I know if my OS is corrupted?

[Andries]

First day, third post

So I have been working through the Virus KC Manual front to back and I am noticing some odd behaviour.

I have been playing around with filter settings as suggested on p 19 of the manual.

But when I press the FILT1 button, instead of selecting the filter (HP, BP etc etc) all kind of weird things happen. The whole synth goes from Single to Multi mode, for instance, or the patch changes to C126 and refuses to produce a sound. Then I have to re-set the synth (switching on + press SHape) again.

Is my OS corrupt? Am I doing something stupid? Any advice would be welcome!