Trying to get into gnus (I think Saturday afternoon CVS), I get the
following backtrace:
Signaling: (wrong-type-argument stringp nil)
  intern-soft(nil [0 nntp+news\.speakeasy\.net:rec\.music\.early nnml+private:websurf nnml+private:linart 0 0 nnml+private:sunny 0 0 nnml+private:pilot-unix 0 0 0 0 0 0 0 0 0 nnml+private:abcdiscuss comp\.lang\.python 0 nntp+news-east\.speakeasy\.net:rec\.humor\.funny nntp+news\.speakeasy\.net:rec\.humor\.funny nnml+private:wwwacct alt\.binaries\.vcd 0 0 0 0 0 0 0 0 nnml+private:world\.old 0 0 comp\.sys\.palmtops\.pilot 0 0 0 0 0 0 0 0 0 0 0 nnml+private:woyp])
  gnus-group-highlight-line()
  run-hooks(gnus-group-update-hook)
  apply(run-hooks gnus-group-update-hook)
  gnus-run-hooks(gnus-group-update-hook)
  gnus-group-insert-group-line("dummy.group" 0 nil 0 nil)
  gnus-update-group-mark-positions()
  gnus-group-mode()
  gnus-group-setup-buffer()
  gnus-group-list-groups(nil)
  byte-code("„
  gnus-1(nil nil nil)
  gnus()
  command-line-1(("-f" "gnus"))
  command-line()
  normal-top-level()

It's still happening with the most recent cvs, and also happens with
ognus 0.3, so it must be something having clobbered my files.

Any suggestions for getting them back?