User roles broken after upgrade, suspect WordPress Wiki plugin

Hi folks,
upgraded to 3.0.1 at weekend just gone and have noticed (could have been there since upgrade to 3.0 a couple of weeks ago) that user roles for the site(s) – we are using WP in WPMU mode have all been replaced by the single option ‘Wiki Editor’.

I assume this is due to an incompatibility with WordPress Wiki Plugin and 3.0.x, especially as the last post on their broken site (no comments actually work) states they should have an update shortly.

Deleting the plugin following a disable has had no effect.

Anyone know of a way to reset the information? Am I likely to have to manually remove entries created by the plugin in the DB?

Thanks in advance

Nibb