Logic Pro 9 Tracks randomly being deleted...??

Hi all,
I have been recording with Logic Express 9 for about a month now and I am nearing the end of finishing my first song. However, the program has deleted two of my tracks without my doing, and I was wondering how i can prevent it! I have 11 tracks, all with recordings on them. Could that be the problem?

Any input is very much appreciated!
Thank you.