a3000 sound and video issues

[Iggypop]

What can be the cause of slight video and sound issues.. besides gremlins, as in for example flickering of the moving spotlight in wolf3d and sound of a certain pitch, sounds crackling.. my gbscontrol not getting a fix on the videosignal.... a monitor all off a sudden getting video timings right, without my gbscontrol. Launch django2 and the screen goes black. and then everything reverts to normal, as in before.

It's just wierd. I dont't see a pattern.. I can'not reproduce the issues... it's driving me mad.. what to check when issues come back ?? It's not te first time I had these issues.