HELP! Tooltips lost!

This morning I started working, just like everyday, on a new model on blender 2.42a (w python 2.4 installed) and I had a bad surprise.
After a while I noticed all the old good yellow tooltips on blender buttons didn’t appear at all! :eek:

So I tried rebooting the pc.
Then I reinstalled blender 2.42a.
Then I uninstalled blender 2.42a and installed blender 2.42a intel optimized, just to test the speed (and, while testing, I noticed neither this version showed me the tooltips!).
Often tooltips help me remember what my little brain can’t remember or give me the right suggestion speeding up my work or teaching me new things in few seconds…!

Somebody can help me make them come back???

User Preferences window => View & Controls => Display options => Tooltips

Thank you…but I’ve already looked at this option and this is selected, but nothing happens…
any other suggestion?