Request object error 'ASP 0104 : 80004005'

We are beginning to experience a problem uploading pages to our server. It would appear that the file size limit for uploading has been reached causing the error. It manifests itself by the error:

Request object error 'ASP 0104 : 80004005'
Operation not Allowed
/ScriptLibrary/incPureUpload.asp, line 62

All suggestions we have found so far, relate to solving the problem whilst running IIS6. We are using IIS7 and cannot find a solution for how to increase the maximum files size.

Any help would be greatly appreciated.