On new projects, hovering the cursor on a track and then rolling the mouse wheel makes the tracks jump up so I only see the bottom few trax.
The zoom settings are the same as older projects that work fine. (All now time and check V&H)
I went from X1 to X3 then shortly after to platinum. It seems to have started after X1

May be it has changed see this
 
http://forum.cakewalk.com/FindPost/3076505
 
Also do a search on Zoom in the help that is quite informational.
 
I think the mouse wheel just scrolls now, on it's own up/down Ctrl/Scroll left to right.
 
Also F = fit tracks vertical, Ctrl-F fit project to window
 
Found the alt-Scroll wheel will scroll project and current selected track length ways and height wise.

Thanks Wookie. So frustrating when you have an ingrained habit, to relearn the basics