Fortunately I found this post in German which Google kindly translated for me, and it solved my problems.

Since the translation screws up some of the code, I thought I would post the steps here in English in case anyone finds it useful.

Step 1: LAMP

If you don’t already have PHP 5 and Apache2 set up, this will get you started. Open up a terminal and type:
[bash]sudo tasksel install lamp-server[/bash]

Guiding you through setting up PHP and Apache is beyond the scope of this guide, so if you get stuck, check the multitude of guides available on Google.

Step 2: Upgrade LAMP

With PHP 5 and Apache installed, the next step is to install the developer versions.

• php5-dev (otherwise you’ll get an error about “phpize”)
• apache2-threaded-dev (or else you’ll get an “apxs” error)

[bash] sudo apt-get install php5-dev apache2-threaded-dev [/bash]

Step 3: Getting build tools

We’re going to be building from source. If you’ve never done that before it’s pretty easy, but first you’ll need some extra tools.
[bash] sudo apt-get install build-essential [/bash]

Step 4: PEAR and memcached

You’re also going to need PEAR and the memcached binary.
[bash] sudo apt-get install php-pear memcached [/bash]

Step 5: Building libmemcached

You’ll need to get the latest source package from here. You may have to try different versions until you get it working. In 9.04, libmemcached-0.33 worked. For 9.10, it was libmemcached-0.37. As of Ubuntu 10.04′s launch, the latest version was libmemcached-0.40, which appears to install correctly but under actual usage conditions the Memcached::add() method failed to write every time, returning error code 5. I recommend sticking with libmemcached-0.37 for now if you’re running Ubuntu 10.04.

Download the appropriate version with your preferred method, or type:
[bash] wget http://download.tangent.org/libmemcached-0.37.tar.gz [/bash]

Extract the files with your preferred method, or type:
[bash] tar -xzf libmemcached-0.37.tar.gz [/bash]

Move into the extracted directory:
[bash] cd libmemcached-0.37/ [/bash]

Configure the package.
[bash] ./configure [/bash]

Make.
[bash] make [/bash]

Make install. Note this probably will require sudo rights.
[bash] sudo make install [/bash]

Step 6: PECL

Finally, you can install the memcached extension through PECL. [Thanks to Andy Lav for pointing out this very important missing step in the comments.]
[bash] sudo pecl install memcached [/bash]

When this process completed, you should see something like this:
[bash]
Build process completed successfully
Installing ‘/usr/lib/php5/20060613+lfs/memcached.so’
install ok: channel://pecl.php.net/memcached-1.0.0
Extension memcached enabled in php.ini
[/bash]

If you see this, you should be ready to go.

You might instead get a message that says: You should add “extension = memcached.so” to php.ini. If that’s the case, open the file with the following and paste extension = memcached.so at the top:
[bash] gksudo gedit /etc/php5/apache2/php.ini [/bash]

After you save and close the file, restart Apache.
[bash] sudo /etc/init.d/apache2 restart [/bash]

Initially I used the stable release of Clonezilla to back up my laptop’s entire hard drive to a USB external hard drive. No problems at all. However, I hit a minor snag when restoring the system with the stable release in that it failed to re-install grub. Oops. Not to worry though, Clonezilla has an “alternative” release based off Ubuntu (the stable release is built on standard Debian). Since I happen to be running Ubuntu, I made a new Live CD with the alternative Ubuntu release and once again tried the system restore. This time it worked perfectly and my system is exactly as it was at the time I backed it up.

The upgrade was simple as always and I experienced no issues … until I tried to boot up my Ubuntu VM. It appeared to hang during boot up, and finally ended in a kernel panic. Every time.

There’s an easy fix, however, which I found here after a quick Google search. The solution is to change the VM settings for the network adapter from “PCnet-FAST III” to “Intel PRO/1000 MT Desktop”.

What do you need to install Flex on Ubuntu?

1. The Flex SDK
2. Sun Java (needed for compiling the SWF binaries)

Set up and install Flex

Step 1. If you haven’t already, install Java. (If you aren’t sure, go ahead and try this step anyway.) First open up a terminal (Accessories menu > Terminal) and type the following:

[text]sudo apt-get install java-package sun-java6-jdk[/text]

This will take several minutes while the packages download and install. You’ll also need to agree to Sun’s license.

Step 2. Download the Flex SDK. The rest of this guide will assume you saved the SDK to your desktop: ~/Desktop.

Step 3. We need to create a directory for the Flex SDK. In a terminal window, enter the following:

[text]sudo mkdir /opt/flex[/text]

The “opt” directory is generally where optional application software packages live. (More info on the linux file system.) All we did here is make a new “flex” directory inside “opt”.

Step 4. Now we need to unzip the Flex SDK. Type the following in a terminal window:

[text]
cd ~/Desktop
unzip flex_sdk_4.zip -d tempflex
[/text]

What this does is unzip the contents of your download into a new and temporary directory on your Desktop called “tempflex”.

Step 5. After that’s complete, we need to move these files to “opt/flex” which we’ve already prepared for the SDK. Type the following in a terminal window:

[text]sudo mv tempflex/* /opt/flex/[/text]

This will move the contents of “tempflex” into “opt/flex”. If you want to make sure you moved everything, you can type the following into a terminal window:

[text]
cd /opt/flex
ls
[/text]

You should see a list of all the files in the directory.

Step 6. Last step. All we need to do now is let Ubuntu know where the new Flex compiler lives. Type the following in a terminal window to open up “~/.bashrc” in a text editor:

[text]gedit ~/.bashrc[/text]

The text editor will open your ~/.bashrc profile and we only need to add one line (I added it at the bottom of the file, but I’m not sure it matters).

[text]export PATH=/opt/flex/bin:$PATH[/text]

Save the file and close the text editor. Then exit all open terminal windows before opening a new one. This should ensure that your terminal loads the path that we just added.

You should now be able to compile your Flex projects with the “mxmlc” compiler command. To make sure, type the following in a terminal window to bring up the “help”:

[text]mxmlc –help[/text]

Looks good? Great. You’re all set. Happy Flex-developing.