I am at my wits end with this one. I know many have had a similar issue but none of the fixes I've read have had any affect. Backgroud: 1 FE Exch 2007 CAS server 3 BE Exch 2007 mailbox servers 2 BE Exch 2003 servers Until today, the 2007 mailbox users had to use /owa to access email via the web and 2003 users used /exchange. Since this became an issue as I am moving everyone over, I did some troubleshooting to fix that issue. I found the BE mailbox servers did not have the isapi extensions or basic and windows auth installed. So I installed them and then all of a sudden users would login to owa and then be prompted after 30 to 60 seconds with the login screen. Having researched this almost 24 hours straight, I have checked the virtual directory authentication settings, removed and recreated the virtual directories, applied the exch rollup 10 and still this is happening. I have absolutely no idea what else to check or why those installs would have caused this. If anyone has a few more ideas I would be soooo grateful!!

Update: Following another post I found, I disabled forms based authentication and now they are not receiving the constant login. Following this issue the only thing I've seen to fix the forms based issue was to change the owa app pool worker process to 1. This will not work for us as it is already set to 1 so i'm stuck again. Any help would be very appreciated.

Fixed: For anyone having th is same issue and none of the suggestions on the internet seem to work for you either, here is what finally fixed my problem: Look at the advanced settings for the owa application pool. Make sure the virtual memory limit is set to 0