I have created a macro in Excel 2007 with no issues, but when I take it to
work and try to run it using Excel 2003, I keep getting "runtime error 438".

When I debug it takes me to the Line:

Sheets("SHEET1").Select
ActiveSheet.Range("$A$2:$D$3000").RemoveDuplicates Columns:=Array(1, 2,
3, 4), _
Header:=xlYes

Is this not supported in Excel 2003?