XEmacs 21.4.13 hangs after X-error!?

Hi, I have been getting this hangings lately. Suddenly XEmacs hangs or is at least not possible to communicate with. These X errors are reported to the terminal where XEmacs was started. xemacs: X Error of failed request: BadWindow (invalid Window parameter) Major opcode of failed request: 25 (X_SendEvent) Resource id in failed request: 0x1018694 Serial number of failed request: 3931242 Current serial number in output stream: 3931243 Xlib: unexpected async reply (sequence 0x3bfc6b)! xemacs: X Error of failed request: BadWindow (invalid Window parameter) Major opcode of failed request: 18 (X_ChangeProperty) Resource id in failed request: 0x1018694 Serial number of failed request: 3931241 Current serial number in output stream: 3931243 I'm getting this with a late CVS-build, emacs-version "21.4 (patch 13) \"Rational FORTRAN\" XEmacs Lucid" on a RH9 system. Is this a known problem? If not will a backtrace be useful? Yours -- %% Mats