Does your package manager work or is it broken? Can you use apt-get from the
terminal or dpkg? If you can this may have been a temporary problem. If you get
this error message repeatedly then you will have to go back and troubleshoot the
problem.

You can fix apt-get with some of these:
apt-get -f install or apt-get --fix-broken
apt-get --reinstall install [name of program with no spaces or brackets]
apt-get remove [name of program]

and dpkg with:
dpkg --configure -a
dpkg -r bittorrent [name of program mentioned in an error message]

See:
http://www.debianhelp.co.uk/debianproblem.htm
mirror.atrpms.net/ccrma/man/man8/apt-get.8.html

When you have a lock that usually means that there is a problem that needs to be
resolved before you can proceed and a lock has been placed in the package
manager subdirectories. In your case it sounds like the package manager was open
when it tried to place the lock on the package manager and it gave you an error
message. You can resolve it like this:

sudo rm /var/cache/apt/archives/lock
sudo rm /var/lib/aptitude/lock
sudo rm /var/lib/dpkg/lock
sudo rm /var/lib/apt/lists/lock
sudo dpkg --configure -a

I have used this method to fix such a problem. In the end you may have to
manually remove the offending package (xzvf) that caused the lock before you can
fix it. Let us know how you get along.