I havent tried this, but you could either set the tabname.visible=false (dont know if that is allowed) or in the onclick for the tab, create a bit of code that redirects them:
tab_onclick
if me.tab.enabled=false then
me.othercontrol.setfocus
end if
I did actually have this thing working...the naming convention for the tab is odd - I think you have to pass a reference for the clicked tab to the code, and check the .enabled against this, but I did get it working. My problem was where to logically re-direct them to...in the end I took it off, and told them that if all the controls for the tab were disabled, they could ignore it!
Ah...user training...the replacement for bulletproof coding!