I have "lock the task bar" unset and the task bar used to dissapear. It now appears to be always displayed. It is particularly annoying because if you take a window to the top of the screen it displays the bottomn of the window under the taskbar.
This is similar to the following, but in my case it appears to be always in the display position. Why does my Windows task bar pop up and down.
Update -
I can get it back to normal behavior by unsetting and then reselecting properties > autohide. But it doesnt stay that way for long :-(