This can sometimes happen in Mac OS 10.7 Lion.   To fix this,  change the permission of the Preferences folder in your Library:

1. Go to: Mac HD > Library > Preferences
2. Right-click (or Control-click) Preferences and choose “Get Info.”
3. At the bottom of this information page, click the arrow next to Sharing and Permissions.  In side this expanded box, change “everyone” entry to “Read & Write.”
4. Close this window and use your IK software as you normally would.

You may need to authorize once again, but shouldnn’t have to repeat authorization after making this adjustment.