I'm a bit of a newby here, so take this with a grain of salt. But, I had this problem with php4 and w2k and spent days looking for an answer. I had to do a complete re-format, rebuild and re-install. I found a couple of non-specific references to similar problems on w2k after directory and file permissions had been altered for whatever reason (which is exactly what I did). Changing the permissions back does not seem to resolve this problem. If I've missed the mark, I'm sorry, but there may in fact be some kind of obscure bug that doesn't like w2k permissions being changed, even if the change is technically OK.
Andy