Question : HELP! Windows SBS 2008 server keeps hanging URGENT!

HELP! Windows SBS 2008 server keeps hanging.Question: URGENT! Windows SBS 2008server keeps hanging
We have a 64bit, sbs 2008 Server (Standard) with Exchange 2007.  For some reason, it keeps slowing down, networks services are extremely slow, like Printers + Exchnage + File share,  and then it locks up.No I have to hard restart it 1 or 2 time a day a day. I have SQL installed on it.
 Hardware: DEll R710
CPU: 2 * 8 core cpu's (total 16 core)
RAM: 12 GB
RAID: 6 disks, 2 in mirror and 4 raid 5
I scanned for viruses and spywares with nod32 and superanispyware, found nothing
 Task manager show nothing special  
HELP

Answer : HELP! Windows SBS 2008 server keeps hanging URGENT!

I tried every thing!! I had to reinstall the server and that fixed the problem, I hope!