I'm using Access 2007 on Windows XP, and I just noticed a total on one of my forms was wrong. It came down to
 Dim single1 As Single

Dim single2 As Single

Dim single3 As Single


single1 = 425000

single2 = 352922.2

single3 = single1  single2
Guess what single3 equals. 72077.81
Not good for my dollar amount calculations! I did find that the Double type and Currency type got it right, but I'm pretty sure I'll never use Single again.
Obviously this is due to the inaccuracy of representing decimal numbers in binary, but the range of Single would really suggest that you could do math with reasonable size numbers and expect accurate results.
It's amazing to me that in Single math 1,000,000.1  1,000,000 = .125