I am running release 2304 of Chimera under Windows XP with service pack 2 on a Dell Inspiron 9300 laptop. The image disappears from the screen for no apparent reason. With the structures I am currently working on, this has become frequent and often occurs after just a few seconds when I click anywhere in the Chimera window. I have found that if I use Model Panel, I can get the picture back by clicking the 'Shown' box to remove the tick mark, then clicking it again to re-insert the tick. But the picture soon disappears again. Occasionally, it doesn't disappear completely, but part of it collapses, or spurious long lines appear. I had the same problem with a previous release, 2184, and was disappointed that upgrading didn't fix it. I can find no mention of anything similar in the documentation or email archive. Can anyone suggest a possible cause? Peter Girard (University of Nottingham, UK)