Often, but not always, when I want to select a single cell in Excel 2007, two
cells are automatically selected. How do I prevent this behavior? Is there
a problem with my mouse's drivers or is there a setting in Excel that I may
be missing? It's a Logitech Performance Laser wireless mouse.

Also, sometimes when I want to select multiple cells by dragging the cursor
over multiple cells, Excel will instead move the starting cell to a new
location (to the last cell I intended to select). How can I turn off that
behavior?