I bet someone somewhere got really excited when their financial spreadsheet showed $34,465 over their bank statement.
Try this in your spreadsheet program:
Enter the formula =77.1 * 850 into a cell.
What you should see is the result 65,535.
If you're running Excel 2007 (and if you're reading this before the upcoming patch is released) then you may see the incorrect result 100,000 . . . More "accurately," Microsoft says the calculation is correct behind the scenes, but Excel is failing to display the solution correctly.
It appears that any formula that results in one of about 12 solutions triggers this calculation bug.
The specifics for you spreadsheet guru's may be perused at http://blogs.msdn.com/excel/archive/2007/09/25/calculation-issue-update.aspx .
Patch is coming, although it's a guess whether it will make this months patch cycle.
Edit: In spite of the above claim that the error is limited to what's displayed, if you reference the cell that display's the incorrect value in another calculation (this IS a spreadsheet after all, so duh, yes we're likely to do that) the secondary calculation will use the incorrect value too.