Trojan locks user/admin account

I have a friends desktop which is infected with a trojan which prevents getting acces to user account, symptons are when account appears click to log in and screen says Loading Settings....Saving Settings and thats a never ending process. I have slaved his HD in my computer and have just about thrown every bit of Trojan/AV at it and still cannot get rid of it. Also I cannot access his folders to drag off his personal files to do a clean install, difficulty is that I cannot get a report to show here as I cannot boot his pc with the infected drive, and I know not where the trojan lies. I am now thinking on the lines of data recovery tool but that will/may bring the Trojan with it.. any suggestions here Fellow Geeks its a real sticky one. PS several Virus/Trojan references were deleted during extensive scans over the 3 days but this one in particular seems to hide from all scans I have done.

 

Well it appears this trojan has defied all so other remedies called for. I loaded another OS (xp) onto the same ''C'' drive and this then allowed me to use a partition prog to construct another, in here I installed another XP then having done that I then installed a data Recovery prog.. 'Easeus' and was able to recover the music/photos and text files that were important and I hope does not contain a copy of the Trojan. Having achieved the recovery process I then Formatted the 'C' partion and installed XP, installed all drivers then and transfered recovered data back to ''C''..formatted the newly created Partition 'D' then resized. One thing I will never understand is why people never Back up there valuable data.