If you face an issue where OWA in Exchange 2007 stops working, there is a pretty cool powershell command you can run to recreate the OWA virtual directory. The following commands will get you going:

This command will list all the current virtual directories.

Get-OwaVirtualDirectory

This command will delete the “owa” virtual directory under the Default Web Site.

Remove-OwaVirtualDirectory -identity "owa (Default Web Site)"

This command will re-create the “owa” virtual directory under the Default Web Site.

New-OWAVirtualDirectory -OWAVersion "Exchange2007" -Name "owa (Default Web Site)"

When you run this command, if you get an error as follows, it is possible that IIS is set to work in the 32 bit mode and not the required 64 bit mode.

New-OwaVirtualDirectory : An error occurred while creating the IIS virtual directory ‘IIS://mailserver.somewhere.com/W3SVC/1/ROOT/owa’ on ‘mailserver’.
At line:1 char:24
+ New-OWAVirtualDirectory  <<<< -OWAVersion "Exchange2007" -Name "owa" -Website "Default Web Site"

To make IIS work in the 64 bit mode, you need to run the following command:

cscript %SYSTEMDRIVE%\inetpub\adminscripts\adsutil.vbs SET W3SVC/AppPools/Enable32bitAppOnWin64 0

Just in case you do not have the adsutil.vbs script in your adminscripts folder, you can download it from here.

Drop me a line to let me know if this post has helped you!