The size of the scrollbar is inversely proportional to the number of used rows
in your worksheet--a few rows means the bar is large, lots of rows means the
scrollbar is small.
But if you know that you only have a few rows and excel thinks you're using
lots, the scrollbar is much smaller (and then it moves faster when dragged down)
than it should be.
If you hit ctrl-End and excel takes you way past what you think should be the
last used row, then you can reset it using some of the techniques at Debra
Dalgleish's site:
http://www.contextures.com/xlfaqApp.html#Unused
If this isn't the problem, you might find some alternative ways to select your
range. I like to start at the bottom right and go toward the top left. Then I
know I can't shoot too far past my range--I'm stopped at row 1.
You could also click on one of the corners and use the scrollbars to get to the
opposite corner. Then shift click.
Or click on one corner and hit F8 (notice the righthand side of the statusbar
now indicates EXT (for extending the range). Now you can use the mouse or
keyboard to get to the opposite corner. Hit F8 when you're happy with the
selection.
(Remember that you can hit F8 to toggle the EXT feature if you decide you don't
want to use it.)