I have both Visual Studio 2010 and 2012 installed on the same machine. When I load a project I get the message "Loading toolbar content from package 'Microsoft.VisualStudio.IDE.ToolbarControlsInstaller.ToolbarInstallerPackage' {2C2988B35-07DA-45F1-96A3-BE55D91C8D7A}" in VS 2010's status bar and it just sits there until it's done. To fix this problem I've gone through the registry and removed all instances of the GUID: {2C2988B35-07DA-45F1-96A3-BE55D91C8D7A}. This fixes the loading issue; however, I don't have the Infragistics toolbox with the controls.
Have you run the Toolbox Utility?
I did run it as I was missing the toolbox items for Infragistics and that is when this loading issue started. I noticed the utility also installed toolbox entries for older versions still installed (10.x) so I went and uninstalled all previous versions except (2011.1 and 2011.2) and removed all WPF (included 2011.1 and 2011.2) and the issue persisted.
I've attached a log file by running devenv.exe /log c:\temp\ideLog.txt (ideLog.txt)
I then re-ran the "Create Visual Studio Toolbar Tab for CLR4.0"; but, that didn't seem to fix it either. (attached the log ideLog2.txt)