Assumeably you are intending to upgrade to CS6 before you give your computer to your friend.
That may or may not fix the issue with your "timeline". (It may install some system codecs you need or maybe not)
The issue is more to do with the type of footage you have on that particular timeline in that particular CS5.5 project.
What is the footage codec that is missing?
Considering you are giving away the computer...that issue may not be a problem to the new user because he/she will be working with his /her own project and footage.