Not that I intend to try to re-create this problem by joining that many, but is the issue affected by doing a mass-join, or does it happen even if you only join them spaced apart? Does the logging actually fail, or does it log those channels in spite of the error?
Since this kind of error could be related to an operating system, it helps to know which you're using.
Also, how many files are in your logging folder:
//echo -a $findfile($logdir,*,0)