T400 is rebooted unexpectedly

Question

Hello there,
I have a problem with T400 that the laptop is rebooted unexpectedly when I try to logon Windows(at GINA). It's rarely happened. Once it's happened. It become I can not use my Windows account with a message like "You can not use this computer with this account, Please use other computer". It's in Japanese so It will not be properly translated. 
After several hours, I can use the Windows account.
Before shutdown PC manually, USB memory(ReadyBoost) was connected to the laptop. But, I'm not turned on readyboost on USB memory.Anyway I guess It might be a caused.
My environment is below;
T400
BIOS:7UET93WW(ver. 3.23)
Intel WiFi Link 5100 AGN(Driver ver.14.2.0.10)
TPM 1.2
Windows 7 Professional(Japanese) SP1 + latest hotfixes
CSS 8.3
Does someone know about this problem? Please help me.
Sincerely,

Answer 1

hey sbux0007,
the T400 of yours, does it have one user account or 2 and is it being use in an office network? I normally stumble across >> "You can not use this computer with this account, Please use other computer" .. when it is a system that has two user accounts and when the computer is set to use with a network.
since this rarely happens it is hard to pinpoint what is causing this. what i suggest would be that you keep an eye and make notes of what programs that you were using before the sudden reboot.
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