Symptoms
If you read Web pages from a site, an HTML page may be incomplete, or you may receive script error messages such as the following in Microsoft Internet Explorer (Programming) version 6.0:

Object doesn’t support this property or method
-or-

‘(object reference)’ is null or not an object It is also possible that an HTML page may be incomplete.
This occurs when you read Web pages from a site that uses all the following: Script in external files, for example, JScript (.js) filesFrames and script inside the frames that refers to variables or to methods that are defined in other framesHTTP compression to compress the HTML and the script filesHTTP headers that prevent the browser from caching the pages
The symptoms of this problem typically occur inconsistently and may appear random. Sometimes the error messages may appear when you first load the site. At other times the error messages may appear when you refresh the page.
Resolution
To work around this problem, you can do either of the following: If you use a Cache-Control: no-cache HTTP header to prevent the files from caching, remove that header. In some situations, if you substitute an Expires HTTP header, you do not trigger the problem.
-or-
Do not enable HTTP compression for the script files.