There is no camera attached to this computer

Sigh, I've had this problem for a while now and just about exhausted every avenue I can think of but have yet to come up with a solution.

Problem: Accross all apps that use the camera (Facetime / Skype / Photobooth etc). Camera works fine for a while after a restart (mostly - will explain further down) but after a day or so, give or take, I will receive the dreaded "There is no camera attached to this computer." message.

Once this message has appeared, it appears to be game-over until one of the following:-

•Restart Computer (sometimes works)

•PRAM reset (sometimes works - might just be down to the restart rarther than the actual resetting of the PRAM)

•Holding power button on restart until 'beep' (Usually works)

Note that:-

•Once I get this message, the camera no longer appears in the System Profiler.

•Camera functions fine when it's on.

So far I have tried:-

•using different apps: doesn't seem to matter which app I'm using, i.e. if I exclusively use Skype, the camera will still fail. The same is true of photobooth

•doing the above restarts/resetting things: In all cases, the fix is temporary and the problem persists after (usually) a day or so.

•Leaving the app running: I thought if I kept the camera "active" all the time, it might continue to work. Not the case, after a day or so I came back and just had a picture frozen on in and upon restarting facetime, you guessed it, "There is no camera attached to this computer".

•Formatting disk and reinstalling OS: I thought that the issue might be to a conflict somewhere in the preferences etc so did a clean reinstall of the MacOS 10.8 however, note that this has occurred under 10.6, 10.7 & 10.8.

From the above I deduce that either:-

•There is a fault/conflict in the software / OS though it would have to be something that only kicked in after a certain amount of time. Note that I've not yet timed how long until the camera fails as this is somewhat impractical.

•There is a hardware fault that again, only surfaces after a given amount of time. I'm thinking this is more likely after having done the clean install and the problem persisting. I thought I would seek advice on here before "opening her up"!

I've tried to be as thorough as I possible in diagnosing the problem and though there seem to be a few threads discussing how to solve the problem, I've not come accross one where it repeatedly arises.

Thanks,
Jono.