You are using Photoshop CS1 on a MacIntel for which it was never designed.
If you upgrade to CS4, you will have a program that has been designed to run on your kind of computer.
CS1 is not native to the Intel chip and has to be run in an emulator. everyone who ran CS and CS2 on a Macintel had problems with some or all of the pre Intel software.
Is CS 3 compatible with the Intel Mac?
Yes. But the time for upgrading to CS3 is past.
If you are going to upgrade, you would be crazy to install anything other than CS4.
You can still get CS3 upgrades from Amazon.
However, CS3 has some minor UI issues with OS 10.5.5. If you are running Apple’s lated OS, you’d be better off upgrading to CS4.
However, CS3 has some minor UI issues with OS 10.5.5.
CS3 was designed under Tiger and It was not until 6 months after CS3 was released that Leopard was released.