If a user is unable to send or reply when using OWA from home (browser stops responding), make sure they are using the IE icon created by Windows, and not an icon created by an installation program from their ISP (i.e. Earthlink).
If that is not the cause of their issue, you can determine if it’s due to an add-in (toolbars, etc.) by using the No Add-ons mode of IE. This can be found by clicking Start -> All Programs -> Accessories -> System Tools -> Internet Explorer (No Add-ons), or by running iexplore.exe -extoff from the run line.
More info on troubleshooting add-ons can be found here:http://blogs.msdn.com/b/ie/archive/2006/07/25/678113.aspx