UPDATE – as of June 8th, the issue is now resolved. dscr-login-04 blew out a memory module so it is currently running with only 2GB.
Sometime last night, dscr-login-04 went down. Our sys admins detected the problem and attempted to reboot the machine, but the reboot did not bring it online. They are continuing to triage the problem.
In the meantime, you should be able to login to dscr-login-03.oit.duke.edu and use it instead of login-04 — both are 64-bit front-ends, both have the same software installed.
Note that the rest of the cluster — SGE job scheduler, file server, compute nodes, etc. — is functioning normally.