Mobius R: The extra slash doesn't make a difference (and it's .NET that adds it for some reason I've not worked out), Windows just ignores it.
The extra . is because Prodder assumes that the reason it can't copy the file the first time is because you've already tried to play it once but Audiosurf has left it open (there's not a lot I can do about this) so it tries a second file name.
The reason it's not working is because you don't have write access to F:\Dorian\Games\Audiosurf\audiosurfprodder for some reason.
Try copying the directory to your desktop and running it from there. If you get the same problem I'll look into it. The ..mp3 part is supposed to be .1.mp3 instead, not sure what's happening there, I'll look into it.
lavacano201014: It shouldn't be trying to create a tempsongs directory where the mp3 is.

Have you got v0.1 or 0.11 as this is (supposed to be) fixed in the latter.
I'll have a look through the code, but I'm pretty sure this shouldn't be happening.
I guess moving the tempsongs directory (and adding an option to let the user decide) is the best plan for this.
I'll ask the system for the default system temp directory, make a tempsongs directory there and use that by default then add a folder picker in case the user decides they want to put them elsewhere.