For this one, since you can't fix the installed OS you try the "XP REPAIR INSTALL" then if that fails you get your files out and then start over.
Be sure to google "XP REPAIR INSTALL"
Bob
now my windows xp cannot login,first,when it boots up(after windows xp loading screen),it displays windows error:
1.winlogon.exe :the procedure entry point setobjectowner could not be located dynamic link library GDI32.dll
2.lsass.exe : :the procedure entry point setobjectowner could not be located dynamic link library GDI32.dll
3.logon user interface msgina.dll failed to load,please restart
now i have replaced msgina.dll & gdi32.dll,but still cannot login to windows xp,can anyone give me guide/help?

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