Circular Reference with =NOW() entry

I'm guessing there's something else going on in the cell containing NOW().
XL2007 doesn't flag just that function as causing a circular reference.

I never had a problem with 2003, converted to 2007 and these references started popping up only on those cells that had the =NOW() in them. I can live with it, just want to make it go away if I can.

Here's what I just tried:

•Opened XL2003
•Entered =NOW() in cell A1
•Saved and closed the file (Book1.xls)
•Closed XL2003

•Opened XL2007
•Opened Book1.xls....no circular ref
•Saved the file as an XL2007 file (Book1.xlsx)...still no circular ref
•Closed Book1.xlsx

If you delete all of the other cells in the sheet and leave the NOW() cell
...do you still get the circular ref?
If yes....and you delete the NOW() cell....circular ref?

I had circular references in other cells but the =NOW() cells were identified first as having the reference, once I deleted the =NOW() cells the other cells were identifed, fixed those so I can now enter the function without the circular reference.