I thought I've seen everything when it comes to drafting, but no...

http://img118.imageshack.us/img118/5445/draftexploreryj2.jpg

I've created a colony and one of those cities is founded on copper, so
the AI won't draft warriors. Guess drafting goes before anything else.

http://forums.civfanatics.com/attachment.php?attachmentid=164732&d=1196187509

This should be a very easy fix. Just change the <iConscription> field under Explorer in CIV4UnitInfos.xml from '1' to '0'. I think it was pretty daft to make explorers conscriptable in the first place -- can't attack, can't be upgraded to anything useful. If push came to shove, I'd much rather draft warriors than explorers. And doubly so for a newly-formed AI-run colony, which can upgrade these at a greatly reduced rate.