IE7 + Tabbed Browsing for different Profiles

I have a user who cannot get Tabbed browsing in IE7. The administrator account can on that PC so I am assuming that the tabs are something to do with the user rights.
PC runs XP Pro as a domain member PC on a Network running Win2k3.
I have tried all sorts of things – Re-installing IE7, running with no add-ons and all the suggestions in this site (http://msmvps.com/blogs/spywaresucks/archive/2006/10/24/203178.aspx)
The only thing I have not done is blow away the user profile on the PC.

I was just wondering if any one knows what registry key to tweak for rights – if any, or what other suggestions to try?