SMP and NFS

[M]

I have a system that is being used as a high performance NFS server

FreeBSD nfs2 5.3-RELEASE-p2 FreeBSD 5.3-RELEASE-p2 #1: Tue Jan  4  
19:14:40 EST 2005     root at nfs2:/usr/obj/usr/src/sys/NFS  i386

Two CPUs (tried hyperthreading and not), 4 GB of memory

CPU: Intel(R) Xeon(TM) CPU 2.40GHz (2400.10-MHz 686-class CPU)
   Origin = "GenuineIntel"  Id = 0xf29  Stepping = 9
    
Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE 
,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HT
T,TM,PBE>
   Hyperthreading: 2 logical CPUs
real memory  = 4160225280 (3967 MB)
avail memory = 4073271296 (3884 MB)
FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
  cpu0 (BSP): APIC ID:  0
  cpu1 (AP): APIC ID:  6

The NFS exported filesystem is on a Q-Logic FC card

isp0: <Qlogic ISP 2312 PCI FC-AL Adapter> port 0x4000-0x40ff mem  
0xf8300000-0xf8300fff irq 28 at device 3.0 on pci3
isp0: [GIANT-LOCKED]

The disk is formated UFS2 and is big, but not *that* big yet

/dev/da1s1d 471860682 206516934 227594894    48%    /usr/local/export

Every 12  hours or so the system crashes with a hard lock and no error  
messages in /var/log/messages or on the screen. I've moved all the  
disks to a duplicate system. If it continues to lock hard what's the  
possibility the issue is SMP?