Zorin: 2 Errors

Firstly, when I try to update it says

W: Failed to fetch http://deb.opera.com/opera/dists/stable/Release W: Some index files failed to download. They have been ignored, or old ones used instead. E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem.

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Second, from the Software Center I installed Matlab which basically just helps installments. But it's annoying and I want to remove it. I click remove in the Software Center but it doesn't do anything actually. Everytime I try from Synaptic, when I click to open it says: "Unable to get exclusive lock This usually means that another package management application (like apt-get or aptitude) is already running. Please close that application first." First how do I fix that? Second, what's the command line to remove Matlab? Thanks a lot!

Ok, I found this too

W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://deb.opera.com stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E585066A30C18A2B

The question is, how do I fix that? Thanks!

Just in case you need, the full note is

Ign http://ppa.launchpad.net precise/main Translation-en
Fetched 1,390 kB in 2s (602 kB/s)
W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://deb.opera.com stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E585066A30C18A2B

W: Failed to fetch http://deb.opera.com/opera/dists/stable/Release

W: Some index files failed to download. They have been ignored, or old ones used instead.
E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem.

Hi,

Those codes didn't work.. I still get the same error I mentioned above. Is there any other way? Can't even open Synaptic Package Manager... I feel like this isn't an error but Matlab is bein annoying and I can't even remove it. How do I ge it so it could update and not get an errror doing so?

Darn.... Okay then. I shall do so. Can I ask an opiniated question? What is your favorite Distro? I assume you use Zorin because it's Zorin group? I'm probably still sticking with Zorin I am just wondering what others you like. Thanks for all of your help!