The JSTOR technical team are working to resolve issues that are affecting incoming full-text requests from link resolvers (such as SFX [Find it @ NTU]) for some (but not all) JSTOR content. Some requests from SFX to articles in JSTOR journals may currently result in errors. JSTOR reports the service is:
currently experiencing some technical issues with inbound OpenURL linking. While these issues do not affect all articles, we do acknowledge the inconvenience here and are working hard to resolve the issue as quickly as possible. […] Unfortunately at this time we do not have an estimate of when this issue will be completely solved, but we appreciate your patience.