outlook 2007 reading pane changes from html to text

[Yama]

When I first scroll to an unread message, the mesage appears correctly in
html, but if I scroll off the message and return to it later, it is
jibberish...perhaps text with all the codes. I don't want that to happen.
Any clues?

 

[Roady [MVP]]

Sounds like an addin mangling the message after you open it.
Can you reproduce the behavior in Outlook Safe Mode?
Start-> Run; outlook.exe /safe
In not, it's definitely caused by an addin.
See http://www.msoutlook.info/question/88

The messages that now show mangled are probably beyond repair.