You mind supplying some of the details of your setup?

Hardware details?

Have you tried alternative hardware?

Lots of users here (including myself) have used Open-E with Virtual Iron and Citrix Xen Server, so it may be a hardware failure or just some additional tweaking/tuning.

Have you tried connecting to the target from another host? Try that and try running some sustained seq i/o through iometer or hdbench or whatever your favorite tool is through the disk.