Cluttered screen

Until recently SL has been running fine on my Macbook with a Leopard OS. But at some point I must have turned on a setting which has made my SL window fill up with some sort of computer code or logging - thin white lines of text and numbers blocking about half of my view. I have tried for hours to fix this, but no luck. Has anyone heard of this problem and knows how to fix it?
Thank you for reading this.

There are some console overlays in the Advanced menu, probably one of those is on. Try, in turn, Ctrl-Shift-1, 2, 3, 4 and 9 to toggle them on and off until you find the one that's in your way.

Thanks, Viktoria, ctrl+shift 4 took care of most of it. Great improvement!
There remains, hovwever, one block of information listing number of avatars visible, nodes visible, batch min/max and lots of other stuff, and that is still there. You have a miracle cure for that one, too? Thanks in advance!
- Mof -

Yes we can kill that one too! Under Advanced->Debug Settings, find DebugShowRenderInfo and set it to FALSE.

(Ah, that's where it's hiding on the menu! Advanced->UI->Show Render Info, wayyyy at the bottom)

Thanks again, it worked. My SL window is now clutter free. How on earth do you know these things? And - how did I activate these settings?????
What I love most about SL is its vast population of helpful and friendly ppl. Thanks again, Viktoria.