My taskbar occasionally refuses to autohide, which can get very annoying. This issue has been raised repeatedly in other forums, with no real solution. A very similar problem has existed in Vista and XP for many years.
Currently, my own problem seems to be caused by one particular open program: if I close programs one at a time, the problem will go away when the offending program is closed. But it’s not always the same program. Most recently it was Adobe Photoshop Elements Organizer v8. As soon as I closed it, the taskbar hid itself. Re-opening the program did not cause the problem to immediately recur.
Various solutions which don’t help at all, or don’t work consistently, or solve the problem only temporarily, have been proposed on other forums:
— uncheck “lock the taskbar”
— reboot
— re-install OS, either from scratch or via an older image
— uncheck autohide in properties, apply, re-check autohide
— check for virus
— turn off anti-virus or other security software
/Dave