Changing site name

I've looked (briefly) at drupal as one of a set of systems several times - and I've always backed away since it has a higher learning curve than some of the others.

However - I've just installed 4.6.5 to beat that pesky curve :) All the others end up without the flexibility I need :)

So - it's going quite well - been spending some time understanding the taxonomy stuff and how it relates to the forums etc.

Now - I've been playing with the values in the administrate > settings page - and everything changes just as I want apart from General Setting -> Name:

Each time I change this then save I get "The configuration options have been saved." - but the old value is back.

Since this is the text that appears in large at the top of each page - I'd really like it to change :)

I'm just a bit too new to Drupal to even know how to go about troubleshooting this one - any guidance appreciated :)