Problems when trying to download updates

So when I am trying to download updates through my Synaptic Package Manager, I get all the way through except at the final file when I receive this error:

GPG error: http://ppa.launchpad.net hardy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 39456311108B243FFailed to fetch http://dl.google.com/linux/deb/dists/stable/Release Unable to find expected entry main/binary-lpia/Packages in Meta-index file (malformed Release file?)
Some index files failed to download, they have been ignored, or old ones used instead.

I am a total Ubuntu n00b, 100% thrown into this OS without a clue as to what I'm doing which has been fun albeit challenging and so I am at a complete loss as to what this means or how to fix it.

Any help is greatly appreciated. Thank you!

Try...

Adding the repository keys to the keyring. OPen a Terminal and issue the command:

sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 39456311108B243F

Tip: If you have a wheel mouse or 3 button mouse you do not need to type commands into the Terminal. Highlight the command written on the page. Move your cursor anywhere in the Terminal and press the wheel or middle button. Automatic Copy and paste! No spelling mistakes! No Typos! No other errors!

First off, thank you!

I tried this as follows:

:sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 39456311108B243F

Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --secret-keyring /etc/apt/secring.gpg --trustdb-name /etc/apt/trustdb.gpg --keyring /etc/apt/trusted.gpg --recv-keys --keyserver keyserver.ubuntu.com 39456311108B243F
gpg: requesting key 108B243F from hkp server keyserver.ubuntu.com
gpg: key 108B243F: "Launchpad PPA for uljanow" not changed
gpg: Total number processed: 1
gpg: unchanged: 1

But then when I run my updates, still the same message! Any other suggestions?

Miss out the colon! It should

Miss out the colon!

It should be
sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 39456311108B243F

And NOT
:sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 39456311108B243F

I did it without the colon!

That was just designating where my line started :)

Still having issue with this!

So any extra feedback is ever so helpful!