Sometimes when I'm setting up a worksheet and I left-click in a cell,
multiple cells in the same column are hi-lited. After it happens the first
time, it continues as I move through the worksheet, reducing my ability to
get work done considerably. After some trial and error, it seems to occur
when I've been adding and/or deleting columns and/or rows, after a header has
been installed. I can move throughout the worksheet using the arrow keys,
but it is a time consuming and cumbersome technique. I think the version I'm
using is Office Professional 2007 (file extension is xlsx). Any help would
be appreciated.

Thanks,