Bad pool error help!

I chose to install N360 this morning as we had spam issues last night. It down loaded and as it launched I got a blue error screen that says bad pool and I can't get past it.. Dell computer with windows XP.I'm a computer idiot, either it works or doesn't. I'm afraid I caused this as we had Live One Care and when it ended we Installed the free Windows Essental. Did this cause the problem ?  How can I fix this? It goes right to that error after I unplug and reboot. Any help ??

THANKS