I have IE and OE6. OE6 is setup to show the preview screen. (that's the way I like it).
If I switch Identities for my partner to read her emails I get the same setup. She can then read and respond to her emails. When she then Switches Identities back to my email account there is now no preview of emails. All I have is a grey screen where the preview used to be.
If I try to open another OE nothing happens. I have to switch off and then switch back on again for the problem to be solved.