Please detail ALL you have done so far in the way of troubleshooting? Need this info to avoid the been there done that scenarios. For instance, have you tried restarting your comp?
iPod touch, iOS 5
Conflicting info: iOS is for mobile devices. We need to know which OS version is installed on your computer.
Which model iMac? Your issue is w/a comp not an iPhone as shown in your profile.
Please update/correct your profile so that you can receive the correct troubleshooting suggestions. This will assist the users in trying to help you. Thank you.