We also have EXACTLY the same problem!
We rent our DVD/VCR, so don't have a manual. The child-lock has always been annoying (it turned itself off a few months ago, but then came back on again. We have no idea if it was something we did without knowing or just an arbitrary switching on and off). However, we were burgled last week, and our friendly local theives took ALL our remote controls, along with the TV.
So we still have a dvd/vcr player, but no remote. And the child lock on. Bah. I did a web-search to see if I could find out how to take it off, and this is the first page that came up!
It's not so much a child lock, as a padlock.
If I find anything, I'll post it here.
Laurie, October 2007