Excel copy, missing cells when paste - Help!

Usually, I can solve my Excel problems with a few searches, but this has taken me for a loop. When I copy a set of consecutive column cells, they are split with dotted lines (see attached image) and do not copy over properly when I paste. I am missing cells when I paste to the same or another spreadsheet.

One thing to mention is that this column was filtered to remove duplicate cells. I think this is where the problem lies, but cannot understand what to do to fix the problem.

I am having this problem with Excel 2007 (win xp) and Excel 2008 (Mac OS X 10.6.6).

I have literally wasted a couple hours searching for solutions with no avail, any help is greatly appreciated as I am on a deadline.

Thank you