From the folks at JSTOR:
On Friday, September 9 and Saturday, September 10, JSTOR will be performing site maintenance that requires a “read-only” period for these two days. During this scheduled maintenance, users will be able to search, browse, and access and download PDF files for content in JSTOR. They will not be able to save citations, reset passwords, create or update MyJSTOR accounts, or purchase articles.
We apologize for any inconvenience this may cause, and appreciate your patience as we work to improve JSTOR.
Please feel free to contact support@jstor.org with any questions.