As part of the recovery from their recent server breakdown, SETI@home have updated their servers to the latest BOINC source tree - partly, I believe, because they also moved from a Solaris server to Linux.

Users using any form of the anonymous platform mechanism are finding that they get "HTTP internal server error" whenever they request new work. Users on project-supported platforms can get work by disabling anonymous platform: users on non-project-supported platforms (OS/2 Warp, 64-bit) are left high and dry.

I have logged a trac ticket (#194), but any project admin thinking about upgrading server software in the near future might like to check this problem first.