i cant boot up my computer

i found my computer was infected by trojan 'infostealer'. i use norton to clean it.
but it always pops up a window telling me that a virus has been removed and i need to click 'ok' to close the message box. it keeps on coming out and the filename it cleaned it different. I read the removal notes in Norton and do as it told me to do. It advise me to turn to safe mode and scan the drive. So i turn to safe mode and reboot.
when the screen comes out with 5 choices to boot.
safe mode
safe mode with internet
safe mode with comman prompt
last time configuration
start windows normally.

i tried every one but it boots up and go back to the same screen again.

can someone help ?


thanks very much