Server Unixware hang up

Hi,

I,ve a Unixware 7.1.4 Server, that it works OK, but suddenly it's hang up for six hours. In the server's console appears the messages of the registration product, the same that appears when the machine restart normally. while thats messages appears the console is lock and the server is out to the machines.

I'd tested all files, logs and I didn�t to saw nothing abnormal.

Any idea, I need help....

Thanks