Topic: Freezing Rails installations. pros and cons?

Hi all,

I've been developing a RoR application for about 2 months now, working with a team of 3 developers. We have had some issues in the application and when applying migrations because some of us had some different versions of some libraries, and on the QA server, which is a third party server (Dreamhost) where Rails components are constantly updating (for example I had Rails 1.1.6 and another guy had Rails 1.2.2, and QA server has 1.2.3 I think).

I think the best solution to avoid this kind of issues is to freeze Rails installation on the application, so that everybody uses the same libraries/components.

However, I would like to know if there are any known pros and specially cons about freezing Rails installation.

I know it's a general question I'm asking, but at least I would like to know where can I find some good information that explains in deep details about this feature, since I have searched for it but coulnd't find anything good enough.

I would really appreciate your help. Thanks in advance!