A specific reference of mine does not work, when others from the same site (and even the same journal) do:
the bad one (could not save):
http://iopscience.iop.org/0741-3335/37/1/002
"good" ones (from the same journal):
http://iopscience.iop.org/0029-5515/50/3/035001
http://iopscience.iop.org/0741-3335/52/9/095005
http://iopscience.iop.org/0741-3335/48/1/008

I also thought it could be an "age" issue (the article is 15 years old), so I tried others from the same year, which did not work, either:
http://iopscience.iop.org/0741-3335/37/1/004
http://iopscience.iop.org/0741-3335/37/1/003

Hence I think this must be a database issue in connection with age.

Could this be some form of unique problem with the record in question?

Thanks,
Janos