Save your current playlist and then clear it
Extract, and install the attached in this post.
Reopen Winamp and put one of the offending files in your playlist and play it once.
Close Winamp (and I recommend reinstalling the current release version (build 36)).
Doing so with the attached build will generate a log file on your desktop named "OpusFileNamesLog.txt". Please attach it in your next post.
Forgot the attachment.