From time to time, i've got a similar issue. Never with my DVD player, but with my digital cable box.
For whatever reason my cable provider will do some form of update, sweep, or other voodoo to the system. they can't explain.
I know when it happens as it always causes the HD output to change format. When this happens i have a HDCP handshake/sync issue, but only through the 990.
I have owever discovered that accessing the box's guide or menu, a static image, seems to allow the handshake/sync to re-establish and my issues disappear.