It’s unsupported. I’m afraid you’re on your own.
If you have a Time Machine image of a working version of 10.10.1, try turning off the Auto Update in the App Store and then restore that version of your operating system.
As CS4 is not supported anymore you will have to upgrade to a later version.
Even if it was running on 10.1 I would not recommend to go back, as it was also an unsupported OS and it is not guaranteed that it would always work and you would have to live with bugs which have been repaired with 10.2 from Apple.