First I was using Zone Alarm and the crashed file was a driver of it. I switched to Comodo and now cmdmon.sys is crashing. They are crashing though after hours of torrent downloading. So I guess it's not either firewall's fault but rather some problem with my XP again. BTW, the BSOD reports tcpip.sys as the problem and I have to say, I did change tcpip.sys to have more half open connections to optimise download speeds using torrents. Any thoughts on this?