Need XP help. please.

Hello,
my computer is an alienware area 51 m9750 laptop, i just recently purchased it in june, but it had problems and so i sent it to the shop. it returned and worked better than ever for a week or two, but just last night it started getting problems. i was on the internet, when it stopped responding, and then my computer froze. i restarted it, and the first thing i saw was that the menu bar at the bottom was, instead of the usual XP blue, grey, then error notices in boxes looking like that of a windows ME or 98 came up. the error (titled: Windows Defender) read: "Application failed to initialize: 0x800 106ba. A problem caused this program's service to stop. To start the service, restart your computer or search help and support for how to start a service manually." while the error notification pops up it now makes a loud beep. i tried restarting my computer, but it does this every time. the even more immediate problem is that my computer will not recognize any of the wireless adapters
T_T will someone please help me figure out how to fix this? i really need your help...