ZFS pool not working on boot

Hello,
I have a server with two ZFS pools, one is an internal raid0 using 2  
drives connected via ahc. The other is an external storage array with  
11 drives also using ahc, using raidz. (This is a dell 1650 and pv220s).
On reboot, the pools do not come online on their own. Both pools  
consistently show as failed.

the exact symptoms vary, however I have seen that many drives are  
marked as variously "corrupt" or "unavailable" most zpool operations  
fail with "pool is unavailable" errors.

Here is the interesting part.
Consistently, 100% of the time, a zpool export followed by a zpool  
import restores the arrays to an ONLINE status. Once the array is  
online, it's quite stable (I'm loving ZFS btw, thank you to everyone  
for the hard work on this, ZFS is fantastic) and works great.

Anyone have any ideas why this might occur and what/if the solution is?

Any additional information can be provided on-request, I am running  
current from approximately 1 week ago.

-Adam