Error: MSTASK.EXE-Procedure entry point

I’ve never seen this error before in my life:

MSTASK.EXE – The procedure entry point GetDomainDNSNameForDomain could not be located in the dynamic link library, ADSLDPC.DLL

Windows 2000, SP3, IE 6, all patched up. User cannot log onto the domain, but local Admin can log in. MMC Snap-in errors when tring to view event viewer and is unavailable. Any suggestions? Thanks in advance.