Look at how that error message is being generated in the script.
If you upgraded to 10.04, there may still be some pre 2.30 gnome stuff hanging about.
http://osdir.com/ml/svn-commits-list.../msg07451.html
... is interesting - a patch which added a test for gnome 2.26 to the installer config. A shallow reading appears to show that if you do not have 2.26, the error appears. Check on your full script. You want to find out how have_gnome_26 gets set.
Gnome terminal 2.29.6 comes with Ubuntu 10.04 - what does terminal 2.3 have that 2.29.6 does not?