This appears to be a bug with ViEmu 3.0.9 in VS2012 (the RTM/release version). It doesn't occur in VS2010.

If my cursor is in some multipage buffer at the top line of the window, and I hit "k" to move up one line, I expect the window to display one more line of text from above the current line, everything already visible to shift down, and the cursor to remain at the top line of the window. Instead, what happens is a full "page up": the entire window changes to display the contents of the page above the cursor, and the cursor moves to the bottom of the window.

In contrast, hitting "j" when at the bottom of the window works as expected: just one new line is revealed.

Similarly, when I hit "H" to move the cursor to the top line of the screen, it mostly (but not always) does a "page up", the same as if I had hit "Ctrl-B". There seems to be some relationship here, because if I hit "Ctrl-B" first, then (optionally) move the cursor around, then hit "H", it works as expected, putting the cursor on the first line of the window but not scrolling anything. However, if I at any point use "k" to move above the top line of the window, then "H" starts acting like "Ctrl-B" instead.

The same behavior occurs when I use the up arrow to go off the top of the window. If I disable ViEmu, then the up arrow does what I expect: just a single line is exposed; a page up does not happen.

I hope this is a simple fix, because it really impacts how I work!