We set our upload size limit to 40,000 megabytes on our Virtual Server settings.
You access this setting in Windows SharePoint Services Central Administration -> Configure Virtual Server Settings -> [Select Virtual Server] -> Virtual server general settings -> the setting is in Maximum Upload Size. (default is 50 megabytes)
This was very bad. Apparently if the setting is set too high, it’s essentially interpreted to be zero by the application.
Once this happened, not only did we get the upload size error, “The form submission could not be processed because it exceeded the maximum length allowed by the Web administrator.” for any size file, but also, we got the Explorer View error, “Explorer View requires Internet Explorer 5.0 or greater and Web Folders.”
A better really huge setting that ended up working for us was 10,000 megabytes.