If you are experiencing trouble reviewing recorded footage or backing up recorded footage via Internet Explorer, it is likely to be down to the security settings within Internet Explorer.
To enable all features, you should add the DVR address to trusted sites and lower the security settings.

To set this folow these steps:-
- Open Internet Explorer
- Go to your DVR address and login
- Click the Alt key on your keyboard to open up the Internet Explorer Menu
- Select the Tools Menu
- Select Internet Options
- Select the Security Tab
- Click Trusted Sites
- Click Sites button
- Untick 'Require server verification (https:) for all sites in this zone'
- Click Add button (your DVR url should be displayed in the add box)
This will add this to the list below
- Click Close
- Set the  Security Level for the zone to Low
- Click OK
- Close and re-open Internet Explorer
- Enter the address for your DVR and login
The replay and backup functions should now work correctly.

If you are using CMS (Central Management Software) you may also have issues on Vista and Windows 7 due to security restrictions. You will have to run the CMS application as an administrator (right click the CMS shortcut and slect run as administrator from the menu) to Playback and Backup via the network.