Time Stamp Issues in 2.5

I upgraded my site River Ave. Blues to WordPress 2.5 earlier this week, and now we’re having problems with the time stamp function in the Post Write screen. No matter how we change the time stamp, it never registers with WordPress. If I write a post at 5:15 but want it posted at 6:30, it won’t work anymore.

Does anyone have this problem? Is there a fix for it? It’s a fairly vital concern for us.