This can be related to internet security settings in Internet Explorer:

Set up the following while logged on under the end user's computer profile:

1. In Internet Explorer, click the Tools button, and then click Internet Options.
2. Click the Security tab, and then select the Internet Sites Zone.
3. Select the Enable Protected Mode check box, and then click OK.
4. Close all programs and reboot the workstation

*If this does not work, enable Protected mode on the Restricted Sites Zone as well and repeat step 4.