Kmail bombs -- on this very list!

I've been trying to get rid of unwanted messages from this list in Kmail -- and at a certain point, it simply bombs out. When I try to delete these messages, Kmail simply terminates with no error messages or anything else that would indicate the nature of the difficulty. The messages I'm trying to delete are from Sid Boyce at 4:37 and 5:23 today and from Sean Rima at 4:49 today (Jan. 27). I've tried compacting the newsgroup file, but that doesn't help. Any suggestions on how to unstick Kmail? Paul