When creating/editing a role and you use the wizard step "Content Type Security", any item you check/uncheck causes an alert box with the message "change unsuccessful. The page will be refreshed." (quoted exactly)
I am currently using p700 (I first noticed this bug last June, so it's been around a while). The change referenced in the error is actually successful. The iframe, however, refreshed. So, when you go to create a role and set all of the necessary security changes, it takes a very long time. It does work in the end though, but is very time consuming.
In this example I am editing the role for "Contributors" and I clicked on the (x) for the approve column on dmHTML. But it happens for all (x)'s and checkmarks on all columns, core types, and custom types. In this example I was using Firefox, but I believe it happens on all browsers.