The problem is also fixed by editing the blank.aspx (i’ve added a tag)

Thanx Mike!

It does not mather which page I go.
I always get a javascript error: “XML document must have a top level document”
on URL http://localhost/mycompany/_root/Blank.aspx

Is this a related issue and does anyone know how to resolve this?

A couple of observations regarding our environment here.

We have seen this message come up both:

1. Accessing CRM from the webclient.
2. Accessing from the Outlook Client.

http://forums.microsoft.com/Dynamics/ShowPost.aspx?PageIndex=1&SiteID=27&PageID=1&PostID=3742094

This edit to the aspx file that Robert suggests in the above link worked for the Save page on the webclient.

Note on Outlook Client fix:
We were able to alleviate the issue on the Outlook Client by clearing offline files and cookies from IE on the local box following adding the text into the blank.aspx page. (It would have been difficult to convince our IT to agree to remove the Windows Security Update). Seems to have cleared the issue at this point. In this case it worked to leave the security patch. (Feeling lucky)