Oops, sorry about that.
I'm not rightly sure, to be honest.
I noticed that nscrt.dll is listed as loaded in your list of plugins,
though I'm not sure what's calling it.
nscrt.dll was our old runtime library from 5.56 and earlier,
but it's no longer used or shipped with 5.571.
See here for info:
Maybe there's some old component present...?
All your plugins are the latest versions.
The only ones listed that aren't included with 5.571 are Dropbox (which was in 5.55-5.56) and One For Nunz,
and as far as I know, neither of those are nscrt.dll-dependent.
Maybe one of the dll's in the Winamp root folder or .w5s files in the Winamp\System folder are calling nscrt.dll, and if so, then this means that they're not the latest 5.571 version(s).
It's unlikely to be a write-permissions issue with any of the files in:
because then you wouldn't be able to add files to the library via rt-click -> Send To either.
The only thing I can suggest at the moment is a clean install :-(