Error Spark after restrict logon workstation in active directory

Hi all,

My system use OpenFire 3.6.4 on windows server 2003 SP2 and Spark Client 2.5.8 on all my Windows XP Professional workstation. OpenFire server is configured for the AD settings and is working fine. All user created in USERS Organization Unit. In active directory, I restricted user X only logon from workstation Y. On workstation Y, I logon spark by user X, I got a error “user or password is invaild”. Where I unlimit logon, everything is work fine. help me! I don’t understand why.

Thanks!