Default Delimitaor Not working

Hi,

Using a vb.net program to export some data in an xls format.

When I open the file in excel 2003 on my computer with the deliminator being set at "tab" delimited format it doesn't format the columns properly.

I have to go to change the delimited format, but when I do it is already at "tab" so I just click finish and it places all the right columns in the right places..

On other peoples computers not all but some it works fine..

any help please?