I tried your site in IE7. Don't know if this is a clue to the problem or not, but a dialog box popped up with the following:
Quote:
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Error
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A Runtime Error has occurred.
Do you wish to Debug?
Line: 10
Error: 'umTree' is null or not an object
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Yes No
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I'm not suggesting you should know why this is happening, just pointing it out so that Brandon can take a look into it.