panic: spin lock held too long 8.0-STABLE r207638

[Peter]

iH,
   Got a system that whenever I launch another Virtualbox instance, it
will panic anywhere from 10 minutes to several days.  I was able to get
this system to panic constantly yesterday by trying to install Windows
2008, or after it was eventually installed, it only ran for ~45 minutes
before panic.
Some installs panic at around 2% done, most at ~80% and one actually
completed.

Trying to figure out if it's my hardware or what.
I used to have a Windows XP VM running alongside, and the panics happened
about once a week - eventually I got lazy and didn't start the XP VM.
[less load and no swap usage, and no panics for 1.5 months until
yesterday]

Yesterday I tried to install Windows 2008, and in the ~6 hours I was
messing around, it panicked around 8 times [after random amounts of time]

panic: spin lock held too long
 [cpuid either 2,3, or 4 as far as I remember]

4GB of RAM
AMD X4 CPU
8.0-STABLE r207638 amd64
vbox 3.1.6
mostly GENERIC kernel [sched_ule], with firewall/altq compiled in and
unneccessary hardware removed from kernel config.

With just one VM [FreeBSD 8-stable, 2 CPU 2GB RAM] the system runs fine
for months. [it's also a file/print server]

As soon as I try to get a Windows VM running on there, and it starts using
some swap, anywhere from 20MB to 150MB it eventually panics [usually
within an hour or so].

Any ideas ? hardware issues?
Anyone successfull in running several VMs on FreeBSD -> VirtualBox ?
[overloading it?]

]Peter[