WD Webcam capture still trying to capture webcam with "use image file instead"

OK I am no longer using my usb webcam. Instead I am using an image file and so in capture settings I have “Use image file instead” selected. The video capture device dropdown box is now blank, and the image file is being processed as it should be. However, every so often it’s trying to connect to my usb webcam (which is now disconnected from the computer), and capturing a blank instead of the image which it is supposed to capture. The occasional black frames that it is capturing are breaking my videolastday.wmv file, and I am manually having to go through the webcam images, and remove the duff frames. It’s probably switching to the webcam every 30 mins or so, and capturing 2 duff frames. How can I fix this?

Here are some more details if someone might be able to help. The image file I am using is a webcam image that’s being uploaded to my server from another source. It gets uploaded every minute. I’m using http download to download the file, and I’m grabbing it with WD’s webcam capture, adding overlays etc, and generating it every 30 secs.

When I get the bad frames, it’s switching to my matrox video capture card now that the USB webcam is unplugged. I just rebooted, and when it all came back up I was only getting bad frames, even though in the WD webcam preview I was seeing the downloaded image as it should be. Now after restarting, and making random changes in WD webcam, it’s gone back to producing mostly good frames, but with the occasional bad ones.

It also says in the capture list “INFO this clip is not seekable” – what ever that means.

I’m pulling my hair out here! #-o