Next Property [Excel 2003 VBA Language Reference]
If the object is a range, this property emulates the TAB key, although the property returns the next cell without selecting it.
On a protected sheet, this property returns the next unlocked cell. On an unprotected sheet, this property always returns the cell immediately to the right of the specified cell.
This example selects the next unlocked cell on Sheet1. If Sheet1 is unprotected, this is the cell immediately to the right of the active cell.