You may be unable to use a scanner that uses a “Web Services for Devices” (WSD)-based scanner driver to transfer scanned data in Windows Vista. This problem may occur if the scanned data is very large. Examples of scanned data that may be very large are multipage file formats, such as XPS and PDF, and single-page formats, such as EEXIF and PNG.

This problem occurs even though you have installed the hotfix that is described in the following article number in the Microsoft Knowledge Base:

931674 You may be unable to use a WSD-based scanner driver to transfer scanned data in Windows Vista