Indent behaviour under Win2K

I use xemacs under Linux and Win2k to edit SGML/XML files.
I have noticed differences between the two versions :
If I try to indent a region, it works fine under Linux, but the result
is crappy under Windows, and I must use another program (tidy) to
pretty-print the file.

Xemacs under Linux _and_ Win2k : version 21.4 April 2001

I tried with the native version and the cygwin version under Windows,
but to no avail.

TiA. Jany