Have you gone in and repaired permissions to see if something in there could be causing the issue? And, had you done any upgrades prior to this issue?
I did a google search for isight issues, and there is no shortage of threads on various sites asking the same question, although it seems to vary as to what program it is working with vs. which one it isn't. This sounds pretty common, but I have not seen a definitive fix posted anywhere.
Scroll down to post 18, that might help.
http://hintsforums.macworld.com/showthread.php?t=57786
I found this on another thread, might try it in the order suggested.
Thanks so much for the help, mkolesa!
I tried resetting the pram first, that didn't work; then, on a hunch, I repaired permissions and then reset the pram, and it works perfectly again!
I'm not sure what happened, but whatever it was, it's fixed. Thanks!
Also, some good info here about repairing permissions and starting off the back up disk a little ways down the post.
http://discussions.info.apple.com/thread.jspa?threadID=2270809&tstart=165
I had not thought of this, but if quicktime is set to start automatically, this could be causing the issue too. (this is part of the thread I linked above)
I just recently purchased a new iMac OS X and was running into the same problem, getting the error internal iSight camera not detected by Photobooth, Skype, or iChat. I tried the troubleshooting article mentioned above, but it didn't help. Restarting the computer would sometimes help, but it wasn't consistent.
I did have Skype and iChat set to open automatically when the computer starts, and once I disabled that the camera gets recognized without a problem.
So at least on my computer, having video based applications start before the computer has a chance to recognize the camera was causing the issue.
Man, it is amazing how many pages of thread there are about this topic. Check this one, and scroll about halfwaya down to the post by Andy where he mentions having multiple user accounts logged in.
http://getsatisfaction.com/apple/to...r_the_camera_is_in_use_by_another_application
Similar issue, unique approach. Check it out:
http://discussions.info.apple.com/thread.jspa?threadID=2371488&tstart=135
And, one more for you to explore:
http://discussions.info.apple.com/message.jspa?messageID=9775989
This one sounds promising too, as it seems that quicktime was the culprit here:
http://www.philmug.ph/forum/archive/index.php/t-36683.html
IF for some reason any of these do work, please post up what fixed it to add to the knowledge base!!!!