I'm going to guess the database was switched to mils or inches at some point, then switched back...
Like John said, most likely units were switched, perhaps a few times. I've also moved and rotated groups of things with results "off" grid, text in the group seem to be the biggest culprit.
It's probably more trouble than it's worth but you can export components to excel, round-off the coordinates and re-import. You'll need to clean up routing afterward as well. (Bi-directional_Excel_Link.bas). I did it just once. Wouldn't again.