Xp security toolo 2011 stops my downloads and it takes away backround and taskbar. why?

It just stops my downloads when i try to download malewarebytes and it also takes away my taskbar so i cant see time or do anything. I cant click start. The bar is not their. Please someone help me antiver was on my other computer just a few months ago and im in debt. Please someone tell me how to get rid of this without payin.