For anyone who isn't aware that you CAN run multiple instances of HU~
Download Sandboxie and follow the guide here (first page):
http://www.blizzhackers.cc/viewtopic.php?f=172&t=452182NOTES:
-Do not do this on live, or your keys will get banned. This is only useful for playing HU.
-Do not try to update Sandboxie or get later versions. They come with more beefy software that detects fake keys. If you want this for free, you need to use an old version.
-After you've loaded your 4 sandboxes, you must go to Configure -> Edit Configuration and change the value of "DropAdminRights=y" to "DropAdminRights=n" on ALL sandboxes.
-You don't need to worry about loading multiple keys, as HU only needs 1 valid key to run any number of clients.
I use Windows 7 Ultimate 64 and D2SE. Just set your sandboxes to launch from your D2SE icon. Very easy to setup and well worth it