I have CS 5.5, but need to install temporaly the CS4 suite, but when i try to use it after installing a pop up windows appears with that message "Error 150:30" and ask me to restart my computer before use it. I'm sure that there's only one computer using my serial number but when I try to proof on a second computer it tells me that the serial number is activated in two computer already.
Error 150:30 refers to licensing. You need to contact customer service and verify activation count for your software. If it's good then you can follow this steps depending on your OS:
http://kb2.adobe.com/cps/405/kb405970.html for WIN OS
Hope this helps.
Europe, Middle East and Africa