SQL 2008 cluster security dialog

[cc]

Complete installation insanity.

2 node cluster with 2 instances. One instance has already been upgraded to
SQL 2008 SP1 and the other is still SQL 2000, but I am currently upgrading.

Node 1 upgraded the instance without issue.
On node 2, I get to the 'cluster security policy' dialog and enter my domain
group names for the engine and agent. These are the same groups that I just
entered on the other node and that I had used for the other instance. Upon
clicking next, I get "domain group is not valid. to continue, provide a valid
domain group for the sql server service". I have tried browsing to the
domain accounts and the browse dialog the group fine, but still get the
error. I also tried copy/pasting from one to the other...to no affect.

Any ideas?!?!

[cc]

Rebooting both nodes in the cluster solved it.

Stupid.

Should have known.