Image "Insert into Post" from gallery results in 404 error

I am running several instances of WordPress MU and WordPress standalone 2.9.2. I am experiencing the following problem on all installation

When we attempt to add an image from the gallery or media library it results in a 404 error. The initial image upload works just fine, allowing the author to use the “insert into post” button to insert the image. But if you use an already existing image, or if you try to insert the image a second time from the gallery, clicking the “Insert into Post” button results in a 404 error.

I just installed a brand new installation of Word Press MU 2.9.2. I added the buddypress plugin and then tested the image problem and it exists even on the brand new installation.

All installations are on their own domains, in their own hosting accounts. All are hosted on

Anyone have any ideas I can try?