Susan, what do you mean that the page doesn't come up correctly when you use the IE browser?
Are you using Single Sign On in your environment? This is an article that lists common reasons for "server not available"/offline messages:
https://support.ptc.com/appserver/cs/view/solution.jsp?n=CS129947
Does this also happen with a new workspace cache?
If you haven't done so already it may be worthwhile opening a Tech Support case for this as there are a lot of different reasons why this message could pop up. Some Fiddler captures/WGM logging may be necessary to get to the bottom of this.