Laptop Crash Now Frozen

Two computers on a home network, laptop has frozen. Cannot get past request for password. First I had a problem because IE would not load normally (all I had was wallpaper with no task bar or icons) and I had to use Windows Task Manager to access the computer.I followed an online suggestion to use regedit and to type "explorer.exe" in the Winlogon folder after deleting everything else shown. (I did a System Restore first which did nothing and then a Restore point before deleting). Then I tried restarting the laptop but it asked me for a password for each user account. We have never used a password at all. I logged in Safe Mode and entered Administrator which does not need a password and it started to load then logged off and changed user account. I could not get access. I tried to enter Safe Mode with command prompt but it would not let me, just asked for a password. I tried previous good configuration or whatever it is called but it did nothing. I have obviously stuffed it up by deleting what I did and I need to do a System Restore if it is not too late. It will not take the XP setup disk from my desktop computer. The laptop came with bundled software and there are no discs. Any suggestions? I think it will probably need to go to a local technician and I will have to pay megabucks to have him format the hard drive but I reluctant to lose the programmes and data on the laptop and hope there is another way. I also experienced the original problem on the main desktop computer with explorer not loading but I saved all I could and reinstalled XP which worked. I did not do this with the laptop because I did not have any discs for it.I believe a trojan "Small AOK' was responsible for the original problems as AVG found and deleted it. The original problem will still be there I expect but I need to log on in order to fix it.