Currently Being ModeratedFeb 12, 2013 3:00 PM (in response to jrw429)
I ended up phoning Xserve support, which is distinctly different from "regular" support. They tried very hard but were unable to understand the cause of the error or find a way to fix it. However we did manage to get rid of the "Other Purchases" section so that it shows up in the normal "Purchases" area. It still has "An error has occurred", but there is some hope that if Apple releases an update to OS X Lion Server (which I think is unlikely), then I'll at least see the notification.