...
Log out and go in Windows to:
Documents/EA Games/Ultima Online Stygian Abyss/User Data/{AccountName}/{Shard}/{Charactername}
Open the Character Name file of the character affected in Notepad.
Scroll until you find: <WindowPositions name="PaperdollWindow#######" x="something" y="something" />
Generally, the X and Y values will probably be negative (or at least one will)... change it to a positive value in the range of your resolution, save the file and then load the character back up.