im on my compter right now. the problem is occuring on my windows professional laptop.it all started when i downloaded a program that let a back door trojan horse into my laptop. after i downloaded windows defender and used it it said that 2 malicious programs were found and deleted. i also used my sbc yahoo anti-virus and anti-spyware program and they came up with no kind of infections. but i still had this little critical system error icon in my taskbar below and when i clicked on it, it would bring me to a site that had some type of anti-virus program every time. i didnt i download any of the products cuz i already had an anti-virus program that was up to dat and running properly but i did download a spyware program called spyware doctor. i got the official version and scanned for spyware. the results came back with 57 spyware infections, nothing like wat my yahoo anti-spyware said. so i used the advanced tools they had and deleted the infections and it asked me to reboot and so i did. and when the windows XP loading thing finished, it took me to my profile log in thingy but instead of my log in box showing up, a box that says "lsass.exe system error" along with "endpoint format invalid" with and OK button. when i press it OK it restarts and starts the whole process all over again. i tried every possible solution in the F8 button menu but nothing is working, it shows the same box over and over again. any one know how to get my lap top to function properly again?