Using /usr/bin/tar, are there any known instances where it generates a
format which is incompatible with others, such as Solaris ?

I've had repeated problems with it creating tar files with incorrect
checksums (according to Solaris).  I've had different results using
the SunOS4 /bin/tar on Solaris to the native tar for Solaris.

Winzip doesn't appear so bothered by it and NetBSD's tar will still
extract files without any problems.

Why don't I think it is a RAM or similar problem ?
These both fail (at the same location):

netbsd% tar cf - foo | rsh solaris "tar xf -"
netbsd% tar cf foo.tar foo; rcp foo.tar solaris: rsh solaris tar xf foo.tar

and they always fail at the same point.  If I transfer the .tar file to a
different box and then to solaris, it still appears "corrupt".

I'll see if I can generate a case example .tar file of this problem.

PR material ?

Darren