I moved from a slower (but free) host to dreamhost about 6 weeks ago. At first I was happy about the increased speed, and only mildly annoyed by the practice of rebooting my VM whenever my VM wanted more RAM than I'd allocated. Why not just refuse to allocate any more RAM until some is freed up?
Over the past week or so, whenever the server rebooted, Apache wouldn't come back up per my settings and I'd get that default page. I have a site to run and can't go manually restarting Apache because your settings keep overriding mine. I don't know if this has something to do with your recent datacenter migration, but the timing lines up.
I'm sorry to leave. You have polite and efficient tech support, which is rare in this world. I've moved all my stuff back to my old host and while it's still slow, it never reboots unnecessarily or overrides my settings.