We recently received this message from ARTstor about maintenance on their site tomorrow:
Dear ARTstor User Support and Primary Contacts,
Please be advised that ARTstor will be performing an upgrade to our systems on Wednesday, January 23 between 9:00 AM and 1:00 PM EST. During this time, users will still be able to access the ARTstor Digital Library but may experience some slowness. If you do experience any difficulties, please clear the cache on your browser and restart your web browser. If you continue to experience difficulties, please do not hesitate to contact User Services at email@example.com.
ARTstor User Services Team