You can download all the official versions plus the last latest internal build from your account. Yes, you are still able to download the Q2 SP2 official version, but the libs right after it are not available for download any more.
May I ask you to isolate what is the dll causing the problem - is it the "Telerik.Windows.Controls.GridView.dll" or is it the ""Telerik.Windows.Controls.Diagrams.dll"? Have you tried the workaround deleting the design assemblies for the problematic one? Would you be possible for you to upgrade to the next version - 2012 Q3?
the Telerik team