a0494a2a_ng__404_Not_Found_Error__Files__Category
[Comments and examples] Toolbars such as Discuss for Internet Explorer/Microsoft Office may request URLs that do not exist. /MSOffice/cltreq.asp /_vti_bin/owssvr.dll [Category] 
Toolbars
Benign Unexpected URLs - Part 1 - Missing (404 Not Found Error) Files