Creative Suite 3 Serial number
@Arnaud Mélon & @Rajashree Bhattachary So I'm also struggling with this issue, as my original copy of CS3 has had the reactivation issue. Spoke with three different adobe agents via a chat call, and received no solution to the problem. The first agent gave me a link to uninstall and reinstall photoshop with a new serial number... which didnt work the way he said it would. This photoshop is still asking for a serial number and says its a trial version. I've used the serial number given to me by the link to request a new number as well as a fresh version of CS3... Which this new version says is invalid...
I've located the host file, removed it from its folder so i could edit it, then replaced the copy in the folder with the now edited one.. but nothing has changed and still PS says its a trial program that requires a serial number. Please help, I havent been able to work in over a week because of this issue

