Frame based design can easily bring more problems, then benefits for its users and designers. It's always better to avoid it at all... Some of the problems are not so obvious (like, there is no way to keep a link on a particular configuration page - address bar always contains the frame page link instead), others are not. But nevertheless, they create a lot of inconvenience or lead to obvious bugs.
Here are some examples:
1. Frame in frame problem.
There is a lot of ways to get into it. One of them - submit a change and then click on Return
See the picture below:
2. Here is yet another example - if you click on menu in the left frame System Management | Auto Provisioning
(as well as any other 3 bottom items in the menu) the page is opened not in the right frame (as it's supposed to be), but in the left frame instead, replacing the menu itself...
See the picture here:
3. Some pages have broken layout. The picture below shows how Call History
page looks like in IE7 browser. As you can see, the table is far on the right side of the browser. I have to use horizontal scroll bar just to be able to see anything there...
All the pictures above were taken with Internet Explorer 7 running on Windows XP. OBi100 device has v.1.2.0 installed.