Lets see pretty much agreed 3 firewalls are not a good idea but to check what process is using 90% of your resurces just do a ctrl+alt+delete and go to the task manager button then to the running process tab and look for the running process. If you are running Symantex Norton AV if memory serves me their product gets wacked out running live scans now and then and will peg a CPU which usually required a re-install of their product.