I am having te same problem. I tried the suggestion and it hasn't made a difference. Completed downloads still show as incomplete in the Library window AND in my hard drive folders - they have to be renamed manually, and it's looking like so much work at tis point that I haven't done that many - so it looks like I have almost nothing but incomplete files. I think some users may be kicking me for this as well. Truly incomplete files do not load in the Transfer window at all - I have to start over again from scratch.
Oddly enough, these files DO show up as "normal" when I search for them, say, in WMPlayer.
I've been using WinMX for years and never had this problem. The only difference I can think of is that this time, I am using a netbook with Windows 7 Starter Edition; previously I used either my PC with Windows 98, or my laptop with XP.