I'm having a problem with DNN 4.90 expanding/collapsing sections (e.g., Basic Settings and Advanced Settings in Site Settings).

Clicking + or - to toggle a section appears to work at first, but a second later the section reverts to the original state.  Clicking again has the same result.  The section will only toggle when a different section is expanded or collapsed.

Only IE7 is affected, Firefox and Opera work fine.  It happens with the default skin and custom skins.  I've tested multiple installs on multiple servers.

Has anyone else run into this?

I had the same problem and I found out that the anti phishing solution in McAfee caused the problem. I have heard similar stories for Symantec (injecting JS in the page). So check your "so-called" sucurity solutions.

Peter