WebDAV - modifying office files changes mime type

Hi there,

we have a very strange behaviour when we are modifying office files (xls, doc,...) over WebDAV in the Portal KM.

After saving the file and closing the office application the mime type of the file is changed to SGML document definition file (text/xml).

We are using SAP EP 7.3 with Windows 7 and Office 2010.

Does anyone have this issue too?

Any thoughts why this is happening?

Thanks and best regards,

Manuel