Timeline colours

Hi, this is my first post and I have a question I hope someone can help me with.

I’ve just installed Flash CS4 and when I select a frame on the timeline the selection colour is light grey, which is barely disernable from the slightly darker grey of a filled frame. I’ve looked through preferences and searched google, but I can’t find a way to change the selection colour. Also, on my colleage’s computer, who’s also just installed Flash CS4, the selection colour is light blue, which is much better and easy to see. Can someone tell me if it’s possible to change the highlight colour of a selected frame on the timeline? Or is this a bug?