Windows Defender encountered an error: 0x800106ba.

Hi! All,
I was on the field to do some preventive maintenance on our client site. One of the users is using Microsoft Vista. When I started the computer Windows Defender displayed an error message,
I pasted below the whole screen.
Windows Defender encountered an error: 0x800106ba. A problem caused this program's services to stop. To start the services, restart your computer or search Help and Support for how to start a service manually.
After I analyzed the error, I restarted the computer to have a fresh start..After doing so Windows vista stated the same error, so I removed Windows Defender and installed it again, and still same error message showed up upon starting Windows Defender. As far as I know, this is the first time this error of Windows Defender appeared. I don't have any idea now. Should I use another Antivirus? Please share some ideas on my problem.
Thanks.
