Doing (a lot) more checking... it seems that the problem is due to a recent upgrade of the editor vBulletin uses which is CKeditor. We have been working trying to get the editor fully working with IE 10 since the folks at vBulletin have been sleeping at the wheel.
It seemsas though some of the Ckeditor hooks used by both PIE and Tweet are not in the new CKeditor.
I do know that vBulletin is FIANLLY working on the CKeditor to make it IE 10 compatable, once we have the official release hopefully we can fix things.