I just installed the 4.0 beta yesterday and so far everything is working fine except for my custom fields. When I enter data into any of the custom fields and then click "save changes", the info I entered disappears. The "last saved" field updates to the current time, but all of the custom fields are blank again. This happens in IE 8, FF 3.5.7 and FF 3.6.
I thought maybe it might have something to do with the Custom Field titles being defaults, so I changed the titles of the fields through the configuration, and that worked just fine. But I was still unable to save info in the custom fields.
Any help is appreciated, thanks!