Internet Explorer

I am currently running IE 6.0 as I have to have it to run Quickbooks 2004 or greater. However, since I have installed IE 6.0, I have a hard time getting to my ATT webmail through IE. ATT tech support has no suggestions. I can get to the mail through Firefox. I also have IE 6.0 running on my laptop, both run WIN2k and I have no problem getting to the mail. On the desktop, I just get blank screens that say Done, but nothing is loaded. Not even they screen that says Page cannot be found. This mostly happens with the e-mail, but other pages as well. Any insight would be great. Thanks.