I fixed that error by replacing zdll.exp and zdll.lib in trunk/EQEmuServer/zlib/lib/ with the versions I found in zlib123-dll.zip in its lib folder. I got zlib123-dll.zip from the EQEmu Essentials.rar, which I downloaded from a megaupload link I found on these forums. If you've followed recent events, megaupload just got taken down by the US gov. However, their campaign against file hosting websites appears to be in vain, for I went to hotfile and
uploaded zlib123-dll.zip for you. Or you can find it yourself somewhere probably. Anyway, take that US gov!