Active Directory account locks for no apparent reason
Bear in mind that interactive user logons are not the only thing that count as failed logons when it comes to Active Directory account locks. Services that are set to run as a network user and network resources with saved logins can rack up the failed logon count and lock the account.

Hobs' comment to your question is the direction you should head. Check the Security log on the domain controller that the computer authenticates against and you should get the information that you need as far as the source of the failed logons. The fact that it works on other computers only reinforces this. Something is definitely failing, it's just a matter of finding what.