MS Project is not expanding or collapsing with the icon button

I have been using Project 2010. I also has the latest updates. But now It can no longer can expand/collapse groups of tasks using the +/- icon next to the task. It shows up, however when I click on it, it acts like I want to rename the task.

I don’t know what I can do, please give me a reliable and foolproof solution on the issue please

I have tried rebooting, and this is affecting new files that I create as well.

This is ver weird of a problem, I wanted to clarify one thing first, If at all there is someone else logging in to your machine, does it behave as expected? Was the co-worker's file created in Project 2010 or an earlier release?

Please verify these things and let me know so that we can trouble shoot over the issue.

Now there’s drastic improvement in the issue as if it was just waiting for me to open this thread. It is working perfect now

I just reopened the file and it's now behaving as it should (which is odd, because I'd tried to open and close it before posting this as an issue). I'll let you know if it happens again - very strange!