FCE 4 and 4.0.1 compatibility issue:

FCE 4 and 4.0.1 compatibility issue:

While using Final Cut Express 4.0.1 on one machine I save (saves as .fcp) and now when I try to open the same file to continue editing, on a machine running Yosemite, and FCE 4 it gives an error message saying "This project is unreadable or may be too new for this version of Final Cut". I have worked this way before (not ideal), I am wondering if the 4.0.1 update is still available and if so where?

Any Help would be great.

Yosemite (10.10.01) and Os X (10.5.8)