Object has been blocked
From MozillaZine Knowledge Base
The message "This object has been blocked." when downloading files is usually caused by Zone Alarm Pro or other software-based firewalls blocking a certain file type. See below for recommended firewall settings, clear the browser's cache (Firefox 2: Tools -> Options -> Advanced -> Network / Cache -> Clear Now"; Firefox 1.5 and prior: Tools -> Options -> Privacy -> Cache -> Clear; Mozilla Suite and SeaMonkey: Edit -> Preferences -> Advanced -> Cache -> Clear Cache), then try again.
Zone Alarm Pro
Double-click the Zone Alarm icon in the system tray in the lower right corner of the screen. With ZA open, click on "Privacy" button in the left hand part of the screen. Then click on the "Main" tab at the upper right. Once you're in, look in the third section titled "Mobile Code Control". Click the "Custom" button in this section. Four menu items should appear. The last one should say something like "Block mime-type integrated objects". Uncheck the box by this item, then click the "OK" button at the bottom of the dialog box. It should not be necessary to disable any other ZA privacy settings .
CA Personal Firewall
The CA Personal Firewall (formerly eTrust) is based on ZoneAlarm Pro so the same solution applies (turn off "Block mime-type integrated objects" in the "Mobile Code Control" section).