Re: Moving between worksheets in XL
I can't directly help you, but to help figure out what's going on: what happens if you turn on key describer mode, and then press control+fn+up/down?
Does it say what you would expect?
Secondly, assuming there isn't a solution to your problem, you may be able to create a macro to allow keyboard switching of worksheets via some other (configurable) keys.
I rarely use Excel, so can't tell you how to do this, but here is an article where a guy is doing something similar, and he provides some code that you could adapt to your purpose.
I'm not sure what programming language that is (some kind of Visual Basic, I'd guess), but it looks straight forward enough, and seems like it could pretty easily be made to move between worksheets for you.