Keyboard doesn't connect after startup

When i start my imac (2011) my keyboard can't be found, i need to either switch it off leave it off for a while and restart or remove the batteries , add them back and then restart.

This happens every morning If I turn my imac off the night before.

These are the setting from system preferences

Anyone know a fix?

MCAsan said:

What happens when you borrow another keyboard? Does the problem follow the computer or the keyboard?

Click to expand...

Good point... no idea!

I'll see if i can find another keyboard