Yesterday I tried to export a webpart from a SharePoint page in order to see the contents of this web part and understand the working of it. After I clicked on Export, I got an annoying message that the page took too long to save. Either click OK or Cancel. In both situations I could not get the webpart to export.
All my software is up to date. Maybe a little bit too much up to date, as I found out. IE7 worked fine, after installing IE8 it stopped working. It seems IE 8 uses Ajax differently than IE7.
A way to overcome the problem is to go to Tools, Internet Options, Advanced, Security and uncheck Enable native XMLHTTP support.
Note that this is a work around (allthough it will enable you to keep working).