Windows XP login troubles

My brother laptop had some malware on it so he used a cleaner now when it restarts it comes to the classic login from windows 2000 and when you press ok it attemps to login and then says saving personal settings and logging off and goes back to the default login screen not letting you in windows at all. we tried to go through safe mode and it does the same thing. we tried a repair install so we could save his work files and and work programs only to find out we had to only use 256Mb of memory and had to disable the NIC in order for the repair install to not freeze. once the install was complete its doing the same exact thing and he still cant log into windows. need some serious help here guys.