What the hell is this all about? I have done the install a million times and this was the first time I found this error. Seems Office Web Apps destroys everything...there are a couple of different google results around this, but no resolution as of yet (6/11/2010)!
The option of removing OWA from the first server IS NOT AN OPTION (it will break a ton of things). That means I am stuck with a one server farm until Microsoft comes up with a solution for this. Can't believe this wasn't tested...
UPDATE: You must install the latest cumulative updates and this error will be resolved.
Chris