That sounds kind of familiar, when you reinstalled your VGA Planets, did you use your main drive (C:\) for the install? I went through a somewhat similar ordeal a few weeks back and when I tried to reinstall, it couldn't find the target directory to install to, even after I manually created it at times. Finally I had to break down and use the default directory name to install it, I wonder if you have it installed to some other drive letter that might be giving it fits.
Of course, a big part of the problem is that the program is over 10 years old without any major updates, so as time goes on there will be newer and more bugs that pop up.
Tim, please update Winplan for us all someday... please.