SSO with 2 different authentication profiles

[fweigert]

I have two accelerators in the same cookie domain. One of them accelerates a sharepoint site, so I had two add a second authentication profile pointing to the same ou and ldap server as the first one but with basic authentication enabled so that MS-Office applications see the login prompt whenever a document is opened for editing. As a result now I always have to login to the sharepoint accelerator with basic authentication even if I already logged on to the first one via forms based authentication. Does the basic authentication method not use an ichain cookie?
Even though they are both in the same domain I enabled cross domain authentication but that doesn't help either. Is there any way to get this to work?

Thanks