VirtualBox

when install the deb package of virtualbox, u might face this error:

Unpacking replacement virtualbox-4.1 ...
dpkg: dependency problems prevent configuration of virtualbox-4.1:
virtualbox-4.1 depends on libcurl3 (>= 7.16.2-1); however:
Package libcurl3 is not installed.
dpkg: error processing virtualbox-4.1 (--install):
dependency problems - leaving unconfigured

so the problem is about the dependance package libcurl3 was not successfully installed in your ubuntu.

solution:

sudo apt-get -f install

-f Attempt to correct a system with broken dependencies in place

After this operation, 553 kB of additional disk space will be used.
Do you want to continue [Y/n]? y
Get:1 http://us.archive.ubuntu.com/ubuntu/ natty-updates/main libcurl3 i386 7.21.3-1ubuntu1.5 [220 kB]
Fetched 220 kB in 1s (121 kB/s)
Selecting previously deselected package libcurl3.
(Reading database ... 196705 files and directories currently installed.)
Unpacking libcurl3 (from .../libcurl3_7.21.3-1ubuntu1.5_i386.deb) ...
Setting up libcurl3 (7.21.3-1ubuntu1.5) ...
Setting up virtualbox-4.1 (4.1.8-75467~Ubuntu~natty) ...
Adding group `vboxusers' (GID 123) ...
Done.
* Stopping VirtualBox kernel modules [ OK ]
* Uninstalling old VirtualBox DKMS kernel modules [ OK ]
* Trying to register the VirtualBox kernel modules using DKMS [ OK ]
* Starting VirtualBox kernel modules [ OK ]
Processing triggers for libc-bin ...
ldconfig deferred processing now taking place
Processing triggers for python-central ...
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#see version of ubuntu
cat /etc/issue
sudo lsb_release -a

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#fix apt-get upgrade error

sudo rm /var/lib/apt/lists/* -vf

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uname -a
uname -r