Cannot update ubuntu 10.10

I'm really sorry if this question is foolish as I am new to using Ubuntu.

I used wubi to install Ubuntu in Windows Vista, and it was working great up until the second time I had to update.

I make sure everything is checked, then I click "Install Updates" on the update manager and it shows me the Authentication window, I type in my password and then click "authenticate", then it sits in place while it loads something in the background for about five minutes, then it just shows me the update manager again. Nothing was installed and it still showed all the available updates, there was not an error message. My internet connection is fine (obviously) and I've tried several times and had the same result each time.

Again, I'm sorry if this is a dumb question. Any help would be greatly appreciated.