Comping not working

Hi there, has anyone else had this problem. Having been using Logic 8 since it came out with no hassles, and recently did the upgrade to 8.0.1. Now, in this one particular session I'm doing, the comp function won't work. When I go into loop to record, it just creates new regions on top of the old, getting rid of the old in the process (though these still appear in the bin as they should with the correct information). they just don't appear in the arrange secion, and have to be dragged back in manually. It's like it's done everything to make the comp folder, but then the actual comp functions aren't available (ie, not triangle, drop down menus, and only the last take left on top). If I create new track instances and record different takes onto those, I can then manually create a comp folder and it works, but it won't do it by itself. If I open a new session, the comping function works fine, but that doesn't help me on this track, and I've still got a fair bit of recording to do. The session I'm working on is reasonably large, by I'm certainly not anywhere near maxing out.

I'd be grateful for clues anyone can give me.

many thanks,

Elliott