So I upgraded the server, from a pathetic Pentium III 800MHz to a stompin' great P4 2.8GHz. Doubled the RAM too.
But there are weirdisms afoot. This morning I got 404 errors on the site, but things returned to normal once I specified the index page itself, not just the /directory/. A couple of days ago the webserver crashed and didn't recover - that's the first time EVER.
Anyone else notice anything amiss?