The Underfoot download is incomplete when you first get it from Steam. There are instructions here for how to fix it:
http://www.eqemulator.net/wiki/wikka...ssingFilesList
The problem you are describing could be several things. Hopefully you kept a backup copy of the original files from steam. I would copy that backup to where you actually want to run the game from, like C:\EQ, but wherever you choose, make sure it is not anywhere under the Program Files or Program Files (x86) directory.
Then, try again. If it crashes on PEQ you need to also try a different server to narrow down if it is something PEQ specific or global to your installation.
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