I cannot install vtools 3.3.3 in my excel.

error message :
'VTools.xla' cannot be accessed. The file maybe read-only, or maybe trying to access a read-only location. Or, the server the document is stored on maybe not responding.
[ Retry ] [ Cancel ]

I used Ms.Excel 2003 (11.5612.6568) on Windows XP SP2

Thanks for advanced.