I'm not too sure why this is happening, but I can't export my
characters to file in IWD/HOW: Trials of the Luremaster. I wanted
to save one character so I can import another, but the character
file won't overwrite the current character file (if I try to
import the character later, the previous older file will still be
there). When I downloaded TOTLM, I had to reinstall IWD and HOW
first; then, I transferred my previous saved games and character
files to disk (before installing TOTLM). Anyone else experience this,
and if so, is there a way to fix it? I'm lost (and my temper is
getting more sour by the moment).

The same thing happened to me. So created brand new characters and saved. Then I used Dalekeeper and edited them all to be like my original ones. It took a long time but I didn't have to start from scratch.