Luciano, I personally want to thank you for posting the resolution to this issue. We were struggling to find the answer for several days now and we just came across your post earlier today. After disabling TOE, we have not had any 426 errors. We were averaging 1 per minute.
One question, do know if this a documented issue with Microsoft? I searched their knowledge base and came up with nothing. How did you find out about this issue? Thanks again!