hmm it could also be a template problem or a bbcode problem.
make a backup of all showthread and postbit templates, then revert all to the standart version.
does the error exists anymore?
if not, some of the template html code is wrong.
f yes, compare the posts which makes problems if they have used some bb codes or other things which are in every of that post.
to the archiv:
the vb3 archive is a completly different system, it's just for spidering the board, but it's not archivesystem
My hack instead is a true archive which stores whole threads into other db-tables so they won't affect normal vb anymore.
yes it works with 2.30 on my testboard, and not gzip is needed but zlib (which is standart in php4.3 i believe)
it has nothing to do with bandwith save compression, but with true compression in the db