Hi all, I'd appreciate some advice here. I'm in a bit of a hole!

My program is written in Excel 2002. I'm after being contacted by someone
running Excel 2003, and getting a "Runtime error 9 - Subscript out of range".

I know under normal circumstances what this error means, how to locate it,
and how to fix it. So no problem there. However, I've tested my program over
and over in Excel 2002, and haven't been able to reproduce the problem in the
specific area that he's receiving it (Without doing something blatently
obvious like changing a sheet name that can't have happened to his version).
Anyway, I'm waiting for him to send me his specific files for me to check in
order to investigate further. No-one else has reported this or any problems,
so at this point I'm guessing that its isolated.....which leads me to this
post....

In a previous version of the same program, the only issue I received was
from someone running Excel 2003, and now with my updated program, this issue
is while running Excel 2003.....am I seeing the start of a pattern or just
coincidence?
Is there a history of problems with Excel 2003?
Is Excel 2003 a less reliable build than other Excel versions?
Was there some sort of VBA change between 2002 and 2003 that I'm unaware of?

........any ideas about this in general? I'm not asking for error specific
info since I know you can't help without more information which I can't give
right now.

Thanks.