Some editions of MS-Word are not compatible with CSDiff. CS-HTMLDiff, ComponentSoftware new comparison tool, supports all versions of MS-Word. Make sure the Difference analysis tool for the DOC file type is defined as Winword (Internal). WhenCS-HTMLDiff is installed, CS-RCS will use it for revision comparison. This mode is free for users of CS-RCS and does not require an additional key.
You can get CS-HTMLDiff from:
http://www.componentsoftware.com/products/htmldiff/download.htm