Another video source is the built in menu, the remote should have a menu button. If you can see the menu long enough you should be able to find the software version.
On the Visio web site you should be able to download the manual which should cover how to update the software. You should also be able to download any software update and then transfer it to a USB memory stick aka flash drive.
Doubt it is a Roku problem however their online tech support is pretty good. You could try live chat or fill out the web submission form.
http://support.roku.com/entries/413244-contact-support