On the last two 7100 system I set up I would get this message when programming voice mail:
System error:0xO.
I have to open task manager to close the web page at this point. Anyone seeing this.

What version of software are you using. If 4.53c then its recommended that you use the device manager. Also I have ran into issues when using IE 9. Hope that helps.

Firefox works better with it.

I have learned that it happens when you dont fill out an entry completely. If you are doing menu's and don't fill out every part of it, then it will happen when you hit the save button.