Computer will not shut down completely on Windows XP SP3

Windows will close all programs but then it will be a blank black screen and i can still see and use my mouse. I have to hold the power button down on my tower to get it to shutdown(turn off) and when i restart it i don't get any error messages, special boot menu lists or any of the sort. It has been this way for a few yrs now and i cant find anyone else with this similar issue. I hope you can help ***** THIS ISSUE HAS BEEN FIXED. IT WAS RESOLVED A WEEK AFTER I POSTED THIS VIDEO**** P.S. The task bar can but placed on any side of your desktop. Right click the taskbar, remove the tick next to "Lock the taskbar", then Left click and hold the taskbar and drag it to any four sides of the desktop when you reach the side you'll see it pop over.