Horizontal Zoom Problem

Hi everyone!
I’m having a minor issue with Nuendo 7.1 (Win7Pro), but I was not able to solve it.
Sometimes it happens the horizontal zoom “auto-locks”, reaching a certain maximum which it’s really not so high (but it varies), so I find myself uncomfortable in doing precision editing, since I’m not able to “unlock” the zoom.
Most of the time I use Ctrl+Scroll Wheel.
The scroll wheel works just fine, but when it comes to zoom in the horizontal way sometimes that problem occurs.
Also I noticed tha the drop down menu in the lower right of the project window, it’s missing all the preset settings it normally has
Ideas anyone?
Thanks!