IDE in Ubuntu Karmic

I am familiar with Arduino and new to Ubuntu. I got the IDE up and running on my linux machine, but can't get any of my old sketches from Mac OSX to open in the IDE. If I go to the IDE and try to OPEN-SKETCH, I can see the list of all my sketches in their folders, but can't open them. If I try to navigate to the file and then open it, clicking on it directly opens it in gedit, and right click open in Arduino takes me back to the IDE, but no sketch, just the empty IDE. Help?

Is "Use External Editor" checked in preferences? If it is, try unchecking it

Not sure if this will help - but what version of the IDE were you using on the Mac, vs what you have installed in Ubuntu? Also: what are your permissions set on the files on Ubuntu? Is the user you are under a part of the group for reading? If you view the permissions of the files (say, the pde file), along with use and group, are the user and group identified (ie - you don't see a number for the user and/or group)? If you are seeing numbers instead of user/group names, it means the user/groups defined on the mac aren't defined on the linux box (easiest way to fix is chmod/chgrp/chown the files/directories as root); this could cause the issue because you are trying to open/read a file you don't have access to.

All of this is just a guess...good luck! :)