I have the same problem. The application runs on IE 6 w/o problems and on IE7 and IE 8 not. here is a description of my problem:
I have two panels in main window: one FormPanel in top of the window for filters (buttons added to the tbar) and one GridPanel used to present data operating on. Both of the panels are added to the ViewPort (region north: FormPanel, region center: GridPanel). Buttons added to the tbar are used to show filter dialogs which are Ext.Window objects.
Now, everything works perfect in IE6. however, in IE7 and IE8 I have the problem that that when you click on few buttons in FormPanel's tbar, the whole content including panels disapear. Filter dialog window is shown for maybe a second and then disapear everything.
It is really strange that it works with some dialog and with other not. I tried to remove the content from the window object and to show only an empty window - the same result.
Thanks for any help.
Best regards,
erno
Edit:
I tried to show messagebox using js:alert just after the window is shown and it works. if you click on OK in messagebox whole content disapear.