Colors change when copying tab to another workbook

[ChildOKing]

I've encountered a strange behavior that I haven't run into before. I have a typical Excel 2007 spreadsheet that contains two tabs. When I copy one of the tabs into any other spreadsheet, it shows up with the exact opposite color scheme. Neither spreadsheet has any conditional formatting or macros.

This happens whether I copy into a brand new, blank spreadsheet, or an existing workbook. Every cell in the original tab that is set to "no fill color" shows up with a dark gray fill in the copy. Yet, every cell with a light gray fill (header rows) in the original shows up with a white fill in the copy. The only thing that stays the same is if I format the cells to have a white fill in the original tab. Then, when I copy, it keeps the fill color.

It seems like I'm missing something basic here, but I just can't find anything that would cause this. It's easy enough to change after the fact, of course, but this is an action that several employees make daily when working various reports, so it would slow things down. I know a macro could be written to change the colors back after the fact, but it seems unnecessary.

We're running Excel 2007. It happens on any computer we try this on.

Any thoughts as to what might be causing this annoying issue?

Thanks in advance!
Mark