Actually I've researched it and found a person that figured out the issue that he was having almost just like this issue. Here is what he said...
Here's how to fix this problem with IE 8 and Vista.
Microsoft will tell you that you need a hotfix installed on your exchange server, this is NOT TRUE!
Here is what you need to do:
Click "Tools" in the menu bar
Select "Internet Options"
Click Advanced settings tab
Click the "reset" button at the bottom of the advanced settings menu
Close Internet Explorer after the settings reset
Restart IE
On the IE 8 welcome page, click next
Select "do no turn on suggested sites", click next
Select "choose custom settings", click next
Chose your search provider, click next
Select "I don't want updates for search", click next
Select "Turn off all accelerators", click next
Select "Turn off smart screen filter", click next
Choose default browser, click next
Select "yes" for use compatability view updates
Click "Finish"
Then when you go to your Outlook Web Access account, Internet Explorer will ask you if you want to install the "MIME Edit binary behaviuor" add-on. DO NOT INSTALL THIS ADD-ON!!!
This is the add-on that is causing all of your problems, and it can not be properly disabled with the add-on manager. Internet explorer will ask you if you want to install the add-on every time you open outlook web access, and if you install this add-on, you will have to repeat this entire process to get your email working properly again!
Let me know if this fixes your issue if not I'll check for another method for you.