(1) Photo Booth is part of Mac OS X (10.7.x) Lion. Because your mini does not have Photo Booth, and because your external iSight's mic works with your mini's > System Preferences... > Sound > Input but NOT with any application software in any User Account, I conclude that your Mac OS X software haas been modified or damaged.
(2) Properly applying the latest Combo Update for your OS X version may correct the problem. Here's how I apply the combo update:
• Unless you already have one, make a current backup NOW.
• Use your Mac's Disk Utility to repair permissions and then
download and apply the latest Combo Update, for your Mac OS:
currently http://support.apple.com/kb/DL1582
• Repair permissions again immediately following the system restart
that completes the Combo update.
(3) If the problem remains, use Lion Recovery to repair your disk (not disk permissions.) Then restart the Mac and test your external iSight again using the testing methods previously suggested.
(4) If neither of the above helps, use Lion Recovery to reinstall Lion and test again.
(5) If the problem remains after all of this, the only remaining possible fix I can suggest for you is to reinstall all your Mac OS and all other Apple software after a "secure erase" of your startup disk. This reinstall suggestion will take longest, but is the only other thing you can try on your own should all other suggestions fail.
Securely erasing your hard disk and properly reinstalling your software may help if your problem is software. If you need help reinstalling, here is what I am specifically recommending.
• Boot your Mac via Lion Recovery and use its Disk Utility to securely erase (zero) your startup disk. (This can take hours for large disks, so plan some time.) Writing zeros once is sufficient.
• Reinstall Mac OS X Lion.
• After the Lion install is complete, download and apply the latest Lion Combo Update, currently http://support.apple.com/kb/DL1582
• Next, use your Mac's (not Lion Recovery's) Disk Utility to repair permissions immediately following the system restart that completes the Combo update.
• Now use your Mac's > Software Update... menu command to check for an install any other necessary Apple software updates.
• Use your Mac's (not Lion Recovery's) Disk Utility to repair permissions again if you installed any additional Apple Updates.
• Do not reinstall any third party items at this time. Third party items can be either hardware (mouse, keyboard, A/V interface, etc.,) or software (including Microsoft Office or Exchange, plug-ins such as Perian, Flip4Mac, etc.)
• Test iSight functions again as previously suggested. If the problem still exists now, or if it returns in any of the further steps I suggest below, contact Apple or an Apple-Authorized Service Provider (AASP) for service.
• If iSight now works properly with the tests, you can add necessary third-party hardware (if you need any). Add only one item at a time. Test each addition thoroughly and check whether iSight still works before adding the next item. Thorough testing between additions will help you determine if one or more of your third party items is causing a conflict with your iSight.
• If your iSight is still working properly, you can now reinstall additional, necessary software applications. Again, add only one item at a time.
Reinstall additional necessary software from the original disks or download files. Do NOT copy the software from any of your backups because the backup copy may contain the damaged item that is causing your iSight trouble.
Start with the Apple apps that are not a part of OS X (such as iLife.) These Apple apps should not cause any problem, but it is wise to verify that iSight works with each one afteryou reinstall those Apple apps but before you begin adding any other necessary third-party software apps (if any.)
• Check every addition to be sure they are not installing "login items" that may be launching software when you restart your Mac. You can add the startup item back if desired AFTER you are certain that an item is NOT part of your iSight problem.
• Do not copy your data files back until you have tested all the individual additions of apps and third-party items.
(6) If nothing suggested here resolves your problem, your Apple-Authorized Service Provider will offer the only solution I can imagine being successful. There are no user serviceable hardware parts in either your external iSight or the mini's internal components that use it.
Message was edited by: EZ Jim
Mac OSX 10.8.2
