I've got the same problem with v8.14
There was the same problem some time ago
http://www.webyog.com/forums//index.php?showtopic=2947
Maybe this helps.
I can copy ~2k lines, any more than that and i get the same error message. My machine
has only 1 GB ram but it still shouldn't be any problem to copy the data to the clipboard.
Let me know if i can provide further information to help you.