Yesterday, I upgraded the solarphp.com server from Ubuntu 8.04 to 10.04. While this gives us easy access to PHP 5.3.2 packages, it appears to have screwed up Trac. I appreciate your patience while I work this out; perhaps it presages a move to Wez Furlong's "Mtrack" as a replacement.
UPDATE (22 Jun): I have Trac back up and running. Thanks for your patience, all.