I noticed when I upgraded from XL97 to XL2000 on my old machine (but
kept XL97 on the hard disc) that when I wanted to open .csv files by
double-clicking them it took me into XL97. I had assumed that because
there was a valid entry in the file association table when I installed
XL2000 that it did not overwrite it, but that on a new installation
there would not be any entry for .csv in the table so that would be
added and point to XL2000 as part of the instalation process.

I used to get text files with an extension of .DCL, aimed at a
specialist telephone call analysis database package. I set the PC up so
that when I double-clicked these files it would be recognised and
opened by Excel - all the data appeared in column A, and I developed
some formulae in adjacent columns which I could just copy in and down
to parse the data.

I think you probably have a similar situation with .csv files on your
rogue machine. It might be necessary to remove csv from the file
association table and then re-install Excel so that hopefully the
correct association (and action) can be set up.

Hope this helps.

Pete