This happened after upgrading to IE8.0 and is replicable everytime (at least on my machine).
Logging into the administrative panel, accessing the spam quarantine inbox is fine but once I click on a quarantined email, the whole row of "button" links at the top disappears and the whole page would freeze. All links would be rendered unclickable but other tabs within IE are still working fine.
It happens on both my workstation and notebook both upgraded to IE8.0.
Prior to this IE7.0 was working fine.