把40G的空间给了swap交换空间，想收回，怎么办？

新入手Ubuntu，请指教。。。
今天想安装VirtualBox OSE 失败，报：Failed to download package. Check your Internet connection.
之前安装flash也是同样的报错。（后来从某个网站的Plugin提示安装flash安装成功了。）

我总觉得不是网络的问题。
是不是哪里设置不对呢？

去下载一个安装包来装： https://www.virtualbox.org/wiki/Linux_Downloads

使用这个网站上的软件包也是报同样的错呢~
(我双击下载好的软件包，它会自己跑到　software center 然后在那边安装会首先提示在安装不信任的软件，最后还是报failed download package files. 不明白我不是已经download到本地了么？)
apt-get update 也没起作用...

使用命令如下：
anna@anna-ThinkPad-T400:~$ sudo apt-get install virtualbox-ose-qt
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
dkms libcurl3 libqt4-opengl libvncserver0 virtualbox-ose virtualbox-ose-dkms
Suggested packages:
libvncserver0-dbg virtualbox-guest-additions vde2
The following NEW packages will be installed:
dkms libcurl3 libqt4-opengl libvncserver0 virtualbox-ose virtualbox-ose-dkms
virtualbox-ose-qt
0 upgraded, 7 newly installed, 0 to remove and 242 not upgraded.
Need to get 457 kB/21.8 MB of archives.
After this operation, 67.1 MB of additional disk space will be used.
Do you want to continue [Y/n]? y
WARNING: The following packages cannot be authenticated!
dkms libcurl3 libvncserver0
Install these packages without verification [y/N]? y
Err http://tw.archive.ubuntu.com/ubuntu/ natty/main dkms all 2.1.1.2-5ubuntu1
Connection failed
Err http://tw.archive.ubuntu.com/ubuntu/ natty-updates/main libcurl3 i386 7.21.3-1ubuntu1.3
Connection failed
Err http://tw.archive.ubuntu.com/ubuntu/ natty/main libvncserver0 i386 0.9.7-2ubuntu1
Connection failed
Failed to fetch http://tw.archive.ubuntu.com/ubuntu/poo ... u1_all.deb Connection failed
Failed to fetch http://tw.archive.ubuntu.com/ubuntu/poo ... 3_i386.deb Connection failed
Failed to fetch http://tw.archive.ubuntu.com/ubuntu/poo ... 1_i386.deb Connection failed
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

换源！

链接不上
换个源试试

楼上的说法很正确。
我更新了源
从网上找了一些源粘贴进了源文件。 然后又用synaptic Package Manager升级了一下包，装上了。
装的我都快哭了。

感谢~ 感谢~