I have been using openfire on a Windows XP system for some time. Had around 8-10 users connecting to it. The users were a mixture of MAC/Ubuntu and XP users.
They were using PSI and Pidgin.
Today I shifted to Ubuntu and installed the Linux version of Openfire, configured the users but all the users get Generic Stream Error.
Im manually putting in the intranet IP address of my computer along with port 5222.
We would need to see the stream error that clients are getting. You can open an XML console window from your client and paste here the sent and received XML packets. It seems like something is not correctly configured in your new Openfire installation.