✔ 最佳答案
Warning: You have to give all relevant information so other people can return the right answer. I presume you are using XP in your computer. Are you using the correct password to log in? If not or you don't know, stop here and don't do anything hereafter !
First option:
Boot into Safe mode. If OK, click Start > Run. Type:
sfc.exe /scannow (mind the space before /scannow) and enter. Insert your XP CD then follow prompts on screen to run until finished. The CD will find and replace corrupted important system files that stop you from getting into the system. When finished, reboot.
Second option:
Back up all your data, boot with your XP CD and reinstall Windows. Don't select format option otherwise you'll lose everything when finished. Windows will search and replace all missing / corrupted files to make it work.