I'm not sure if anybody else has had this issue, but I've noticed lately that I seem to be having problems downloading custom maps while TF2 is loading.
Case in point, yesterday I tried to join a server that ran ctf_mach4, and when it went to download the map (straight .bsp file) it hung at 0%.
After a few minutes of non-activity, I went back to the server listing and saw that the server definitely was still active and playing that map, so it wasn't a case of the server changing.
Any thoughts? I've also had this happen before, but never thought to document it. I'm sure I can download it offline and just stick it in my steam directory, but I was curious if anybody else has had this problem.