iTunes can't back-up the iPhone

Recently I've had issues syncing and backing-up my iPhone. I continually get the message; "iTunes could not back up the iPhone because a session could not be started iwht the iPhone."

I have restarted my computer (Windows 7), restarted my phone (running on the latest OS 6.0) restarted iTunes also the latest version (11.0.1....). In fact I think this issue started when I upgrated to the latest operating system for my iPhone 4. I don't know how to fix this error and need help.

Anyone?

Thanks