tigger

Aha! Found the solution! The problem was that my VLOOOKUP was referring to its own worksheet by the worksheet name, and when I took that out, it was fine. An example might help: On worksheet DATA, I had this formula for a cell: =VLOOKUP(DATA!A22,CODES!$A$2:$G$664,1,FALSE) Note that this is in worksheet DATA, and it's using cell A22 in that same DATA worksheet to look up a value from another worksheet (CODES). This caused problems when I tried to sort on the VLOOKUP column. But you don't need to say DATA!A22 because we're on the DATA worksheet. You can just say A22, and this means everything works! Just change the formula to: =VLOOKUP(A22,CODES!$A$2:$G$664,1,FALSE) ...and we're laughing! Woo hoo! Hope this works for you too.

I'm having the same problem, and I've checked my relative / absolute cell references and I'm not using named ranges. Don't suppose anyone's found a solution?