Why my field monitor only displays black but audio seems to be working fine?

OL CS3 field monitors only display black. The audio seems to be working and the scopes work fine too. Any ideas?

Thanks.

I have an Acer 1714MSI with a 3.4Ghz processor and a Geforce FX GO5700 128MB graphics card.
I'm thinking it may be something related to the overlay, but I'm not much of a computer expert, so don't really know how to fix it if it is indeed the problem. I use dual monitor sometimes and I know CS3 has a problem with that. So when I run OL I do not have the second monitor connected but maybe some setting is still wrong even if the monitor is not connected?

Thanks.

I would look in the video card display adapter settings and look for overlay settings, primary verses secondary dispaly settings, anything you can experiment with to get it working. Also check for newer video card drivers. If you have two monitors, try the alt plus enter short cut for a full screen preview too.
I have found Creative Cow forums to be some of the best in the world. Just google short digital video questions and see how many Creative Cow answers show up. I don't quite understand the lack of posts on the On Location forum either. It's the same for Adobe Ultra. Both great programs but very few posts. The help files on them are good as are the video tutorials on Adobe's site. Your overlay problem has been on this forum several times because it's not so easy to figure out.
Adobe supports OL if you have CS3 OR CS4 but not if you have the original Serious Magic's release. Little to no difference between SM's and CS3 version except Cs3's works on Vista.
Hope this helps. I monitor this forum several times a week and will gladly help you with anything I can. Danny Hays