Possible to go from 5.5 to 5.4?

[Tuc]

Hi,

     I recently upgraded from 5.4 to 5.5, and now if I leave it in X for a
few minutes it ends up locking up, usually when the screen blanks on
its own. I wanted to go backwards to see if that behaviour goes away.

     I wasn't sure if there was a risk doing this.

Thanks, Tuc