I just did a remote check-in - here are the steps:
1) Create a changelist with a name and a comment
2) Modify some files
3) Commit changelist
4) Change the comment for the checkin from the default proposed by Idea
5) Select Remote Run with checkin if build success
6) Go - the comment flicks back to what it was before I changed it!!
7) The commit succeeds, but with the wrong comment

I have marked this critical because I consider the checkin comments for a given revision to be a very important part of our codebase.
The bug is unfortunately not consistently reproducible

Environment: Idea 6.0.3 EAP build 6117

Issue was resolved