There have been a few problems to say the least with recent comment posted on forums and the like.

It seems that some BlackBerry Tour owners have experienced problems galore with trackball issues. If your trackball has been giving you problems and getting you down in the mouth, great news for you A new operating system version has been leaked.

You can now download OS 4.7.1.53 and give this a whirl to take your mind off of your trackball problems, report your findings to the forums if you find out anything juicy. Please note as always this is an unofficial download and if you choose to download then you do so entirely at your own risk. You can always wait for the official OS release. Source – crackberry.com