Failed attempt to remove accidental HTTP Redirect on Exchange 2007/2010

Hi community,
Suppose you accidentally set up an HTTP Redirect for your OWA on your Exchange 2007 / 2010 and SBS 2008 via IIS7, which was passed on to all virtual subdirectories. You attempt to remove it from the virtual directories (i.e. public, exchange, exadmin and exchweb) but you got the following error:
HTTP Redirect:
There was an error while performing this operation.
Details:
Filename: \?BackOfficeStorageyourdomain.extensionPublic Foldersweb.config
Error: Cannot write configuration file

Does anyone have an idea how to solve this?
Thank you.
