today, I received a PC which alway loged off automatically at once it was logged on.
and I tried to reinstall OS via ghost for it, but it can not logon to Windows properly after OS was reinstalled. it always shows that some files is missing.
and I reinstall the OS step by step not ghost. but it persists after it was joined to Domain.
at last, I replace another Memory for this PC, then the problem was resolved.