Currently Being ModeratedJan 18, 2013 6:45 AM (in response to PaulLuna1981)
Guitar Pro 6 requires an Intel Mac. They apparently should have asked you if you had upgraded to an Intel Mac first. G5s are only PowerPC, which predate 2006.
Currently Being ModeratedJan 18, 2013 1:22 PM (in response to PaulLuna1981)
So I did but apparently Apple is not letting complete the installation because it is a unknown program.
That sounds like you have a much newer iMac than the pre-2006 models this forum covers. Thise models don;t support OS version taht do the security checks.
I think you will get better help with your installation issues and how to work with Apple's security checks by posting in the forum for your verison o the Mac OS. Choose your OS version (do "About this Mac" to see what version you have) from this list of forums: