Photoshop CS5 will not launch either from the desktop or program list. The only way to launch is to log out and restart the computer. At the end of each session I reset the preferences in the Workspace. I am running Win 7 ultimate with 4GB of ram. System is 64 bit . Display is ATI Radeon HD 5700 series. Adapter type is AMD Radeon Graphics Processor (0x68B8). The computer has an Intel(R) series/3400 Chipset Family.
When I installed from the disk I received the message Exit Code 6, 0 fatal errors, 21 errors, 1 warning. I have reinstalled several times and still get the same message. Tried disabling start up items while installing but same message.
One thing that sort of jumps out at me, regarding running the program, is that 4GB of RAM. With a 64-bit OS, 4GB is just about the minimum to run the OS, with little to nothing left over for a program, like Photoshop. I would bump that up, and to 12 - 16GB, if possible.
For the installation, I think that Mylenimum has posted some very useful links.