After upgrading to 2010 Q1, I started getting these errors all over the applications, in all pages using the TabStrip control with MultiPage and TabViews:
Microsoft JScript runtime error: Sys.InvalidOperationException: Two components with the same id 'grPatients_ctl00_ctl27_mpPropertyGroups' can't be added to the application.
The id varies depending on where the tabstrip is placed. The error comes on postbacks.