Server Hang : ACPI disable server recovered :- few queries

[eras mus]

Dear List,

I disabled ACPI in advanced BIOS setup as well as FreeBSD booting opted for
2 boot option ACPI disabled. So Server came to normal , its not hanging and
its responsive at terminals.

When i boot in normal mode it may hang again.

What is the conclusion of this server hang. What will be  the cause of the
hang and
How to fix it?