An account number every day will be lockout, the user tired.
The Troubleshooting method:
The first step, when the account is locked, use the Lockoutstatus.exe tool to determine the login server at that time.
The second step is to save the events related to account lockout with EventcombMT.exe
1) Fill in Domain name
2) Select DC
3 from the menu select Searches-->built in searches--> account lockouts, which will automatically give you the following event id:529, 644, 675, 676 and 681
4) Point Search
The third step is to use Findstr.exe to search for the filtered text file.
Findstr.exe is a command-line tool with Windows installed.
Type findstr/i user Dc01-security_log.ext > \.user.txt after entering the command line tool
This filtered information about the user's account is locked in the user.txt.
The fourth step, open user.txt, look for 644 that line, see which computer is caused by account lockout
The fifth step, to log on to the computer, to see if the following use of this account
1 Automatic Network Letter Mapping
2 the scheduled task or service that runs automatically with the account number
3) There is no broken terminal connection
If you are still unsure which program is causing the account to be lockout, then install ALockout.dll on that computer, import Appinit.reg register the DLL, and restart. Wait until the next account is locked, you can see the log file under%winroot%\debug\ to see which process in particular.
============
Several of the above mentioned tools, you can go to the Microsoft website download ALTOOLS.exe, specific reference account lockout and management tools
Http://technet2.microsoft.com/WindowsServer/en/library/b4145d9a-c4aa-4e0d-b5bc-cb14c7ff69cd1033.mspx
Download ALTOOLS.exe
http://www.microsoft.com/downloads/details.aspx?FamilyId=7AF2E69C-91F3-4E63-8629-B999ADDE0B9E&displaylang=en