I've had similiar problems in the past. For some reason this ONLY works fullscreen for me.
First thing I would do is set EQ back to its defaults. 640x480, the whole nine yards.
Then back the horse up. Undo everything you have tried. Everything.
When sitting at the character select screen, hit CTRL+ALT+ESC and bring up task manager. Go to processes tab. Find eqgame.exe, right click it, set affinity...
1) Click on the checkmark <all processors> and it should uncheck everything
2) check CPU 1 only
3) hit ok
4) close task manager
5) ALT-TAB back to EQ and then if not fullscreen, hit ALT+ENTER
Tada!