[Update] Someone from Telerik contacted me willing to help us out with our issue. That says a lot for Telerik and restores a good chunk of my faith in their controls and their support.
I like Telerik. They have produced some very cool controls to use with ASP.Net. Unfortunately the 2009 Q1 release broke all our controls at work. We normally inherit off of the Telerik controls and add some additional functionality. Whatever changes happened under the hood makes the Q1 + releases useless to us.
My job is to figure out a solution. So far no luck. Telerik says they don't support inheritance issues. Wish we would have known that earlier, or at least known to expect that existing working code will not be guaranteed to work in the future as is.
Sucks. Use this as a warning against becoming too dependant on 3rd party controls, as you can and will get burned.