I find they frequently get stuck open if you have a near-full-screen application open.
Is it possible to disable them?
Open "regedit" as adminstrator.
Find "ShowInfoTip", right-click and select "Modify" and change the value to "0"
You might be experiencing this issue, described on Microsoft's Q/A forum:
The suggestion there is to make sure your video drivers are up to date. For a momentary fix, you can try: