ARD / Screen Sharing Broken on My 10.6 Server

Several months ago, when I updated my SLS server from 10.6.1 to 10.6.4, screen sharing suddenly stopped working on the box. Trying to connect to my server's screen via either ARD or "Share Server's Screen..." in Server Admin would yield a connection failed message. Telnetting to ports 5900 and 3283 would yield a connection refused message. Neither ARDAgent or AppleVNCServer were listed as running processes. Trying to enable ARD using kickstart would return a "Activated Remote Management" message, but did not solve the problem. I held out, thinking that this might be a bug with the 10.6.4 update that might be fixed with 10.6.5. However, after having updated to 10.6.5 (first 10H574 and now 10H575), I still cannot remotely manage the screen of my server. This is becoming extremely frustrating, and I'm hoping someone out there might have some tips as to how to get to the bottom of what's going on, and solve it.