I have recently installed 11.10 and the Update Manager informs me I have hundreds of updates. When attempting to install them I get the message 'requires the installation of untrusted packages'. After closing this, it takes me back to where I came from, hence taking me through the same loop. Any ideas please. Newb.
You seem to have added software sources that are not the Ubuntu official repositories. It is very likely that you wanted to "Add a PPA".
The immediate method to get rid of your problem is by doing the following: in the Ubuntu menu, search for 'Software Sources' and lauch it. Then in the 'Other Software tab', see which checkboxes are checked or not. Uncheck all the boxes under "Independent", "Independent" being excluded. Run the Update Manager again, it should work.
If you still want to add PPAs, follow those instructions: What are PPAs and how do I use them?. Anyway, welcome on Ask Ubuntu!