I think I found the problem. After some brainstorming trough the settings, i activated "ignore the taskbar and startmenu defined in the skin and use the one set below: Wraith ", in skinning settings.
I keep my fingers crossed that the problem won't show up again!!!!
Maybe a lesson for new skinners...
Thanks to yo guys for your great help and support.
p.s. messiah1 , i bought the skin via Stardock, thanks for your concern.