Can you provide a sample that demonstrates the issue?

OK,

Well i have figured out its the XamRibbonWindow and databinding cuasing the issues.

I dont know why yet. But if i dont use databinding to the viewmodel and create the treeviewitems in XAML, it will work just fine, as soon as i databind the treecontrol, wierd stuff starts to happen. IE cant select a node in the tree, UI locking up, and ribbon buttons half grayed out etc...MeasureOverride is also being called a ridiculous amount of times, which is what cuasing the UI to lock.

Its not just treeview though, its even on a data entry form with nothing but textboxes all databound to the viewmodel. It ONLY cuases issues on the data entry form, when i have a scrollviewer wrapped around the content of the form. If i don thave  scrollviewer wrapping it, it works as expected.

If i dont use the XamRibbonWindow, then everything works fine, just like it does on XP.

yes. i am using scrollviewer inside xamdockmanager and make use MVVM pattern.

Are you using a scollviewer anywhere in your xamDockManager?

and

Are you using the ViewModel pattern?

Im trying to narrow this down so i can at least give infragistics a sample app that shows the problem...

unfortunately i can not upload my application. but i check all, and all of my codes are correct.

but it also happens for me.

My UI alos locks.

i also try to create a sample application but it seems to work with the sample.