I’ve had to disable the “FullSearch” moin macro, at least for now – far too many pages were using it, sometimes multiple times on the same page, and each invocation of FullSearch is rather expensive. The result was that the wiki server – which also runs the mailing lists and various other important things – was dying a death.
I don’t know why this has only just started being a problem, because it looks like most of those uses of FullSearch have been in place for a while. But, for whatever reason, it’s a problem now, and the quick fix to stop the server crashing is to disable the macro. Sorry