I am having the same problem however mine is a student edition and it was working fine but now isn't. I have contacted Adobe and they have told me that they cannot troubleshoot CS4 as the version is too old - then I sat with an advisor for an hour that accessed my computer and he just disconnected me as he couldn't solve the problem. The college have told me to contact Adobe, Adobe told me to contact the college.
I am tearing my hair out, I have paid for a web design course that I can not use because of a serial number. Can anyone help its driving me crazy.
I have tried all the troubleshooting on the website.
What problem exactly are you having with the serial number?
The original poster of the thread you posted this message in originally stated that the software was working fine for some time, and then suddenly asked him to enter a serial number.
Is this also what you are facing?
If not, please describe your situation.
Feel free to PM me your serial number and I can check it out for you.
Europe, Middle East and Africa