Ctrl+Space (Move Tool) : Erratic behaviour?

Question

Ok, I've been searching the net for an hour now and can't find the solution anywhere, I'm coming here for backup.
I've been using the Ctrl+Space shortcut for a while and this particular issue is plaguing me since CS4 (Scrubby/Animated Zoom introduction).
Usually, I use Ctrl+Space while on the move tool to smooth-pan around in a zoomed in document. But sometimes, it will zoom the document entirely out and allow me to drag some kind of marquee representing the size of my zoomed view so I can move around like if I were using the navigator. If it happens and I do not let go the space key, I can zoom entirely out and in at will.
It happens mostly when I toggle hastily between the zoom tool and the move tool while zooming, panning (back and forth) the document a lot so I must make a weird combination unwillingly (something like z+space or v+space maybe).
Anybody knows what is happening? I've tried all the combinations of modifiers and can't trigger the feature willingly.
It's pretty annoying expecting to pan away and instead being zoomed out entirely. It feels confusing... like some entity is sucking me all the way to the sky without warning, then tossing me back on the ground somewhere I definitely didn't expect to be.
Thanks.
Edit:
Ok I've found some kind of a trail:
Temporarily zoom an image
Hold down the H key, and then click in the image and hold down the mouse button. The current tool changes to the Hand tool, and the image magnification changes as follows:
If the entire image originally fit within the document window, the image zooms in to fit the window.
If only a portion of the image was originally visible, the image zooms out. Drag the zoom marquee to magnify a different part of the image.
Release the mouse button and then the H key. The image returns to the previous magnification and tool.
Source: http://help.adobe.com/en_US/photoshop/cs/using/WSfd1234e1c4b69f30ea53e41001031ab64-74e0a.h tml#WSA6DF9C40-CEA8-4cfd-9A8B-44108E2975DD
Seems like my combination of keys leaks to this feature: If I hold out H while dragging the mouse, it gives out the exact same behaviour I try to avoid but in my case, it happens when I press Space.
If anyone understands why my Space key behaves like the H key sometimes erratically, I'd really appreciate it.

Answer 1

Yes thank you Dennis. Got to appreciate that expressing something externally often allows to find solutions just by thinking outside the normal train of thoughts.
I've also found out that if you are on any other tool but the move tool, pressing V+Space somehow "leaks" the H shortcut and mimics the behaviour. My particular problem does not require me to hold V (Only Space) but I expect it is a related issue.
Well, no solution possible in the near future except stop going all "Speedy Gonzales" on my shortcuts.
At least now we know how to reproduce the issue.