Problem using filters in Excel 2007

I was playing around with filters (displaying different colors in cells based upon their values), and something I did corrupted the worksheet. There is a lone cell (in the column in which I was doing the filtering) which does not let me modify it, nor can I delete the row in which it is located. It seems to think the cell is now a header cell based upon error messages I am receiving (it is in row 5). I have tried removing protections, removing filters, etc., but that cell absolutely cannot be modified or deleted. Any ideas? I can send the spreadsheet to someone if necessary; it's not all that big.

Here is a screen shot of Excel. The problem cell is H6. If I right-click on row 6, the "delete" option is grayed out. If I try deleting the contents of H6, nothing happens. Well that was interesting. While trying to explain my problem, I noticed that when I selected H6, "Table tools" suddenly appeared on the toolbar, so I selected it and it showed that the cell was a header cell. When I deselected the header cell setting, my problem went away. How in the world I accidentally set that cell to be a header cell is beyond me.

Thanks for trying to assist me.