I have had this exact same issue, I have an 9650SE-8LP card.

I did the same logged a support ticket with open-e on why it didn't failover when the raid card has a hissy fit and dropped the whole unit, that aside, what HDD's are you running in your RAID setup? brand/model and are they on the 3ware support list.

In the end I replaced the card under warranty (it did it to me again). I haven't been able to fault the new card.

I worked with 3ware a little on it, (but didn't get far as I didn't' have supported HDD's) which is what 3ware seemed to think the issue was, the HDD's were pretty much reporting garbage to the 3ware card (incorrect spindle speed's, drive resets etc)

Cheers
Adam