i've been adding words to the USR (user) dictionary, but recently I had some trouble saving a new entry and had to exit Plecodict as it was saving. So the whole USR dictionary is screwed up. it's a bunch of gibberish now.
This happened on Palm? Very odd... anyway, to delete the user dictionary download and install the free utility FileZ from http://www.nosleep.net/, run it, tap on the "View and Edit Files" button, tap on the triangle next to "Internal", scroll through the list of files until you find one called "PlecoDict User DB", tap on it to select it, and then use the Delete menu command to delete it.
For that, exit PlecoDict completely using the Quit command in the Dict menu, then open up File Explorer, navigate to your My Documents folder and delete the PlecoDict User DB file in there. (if there are more than one, delete them all)