The wireless cards in a lot of laptops need extra drivers to work so
you first need to connect using an ethernet cable then get additional
drivers - mainly applies to Broadcom chipset cards. However even if
you boot up with the Ubuntu CD and have that ethernet connection it
will alert you to the need for additional drivers and you can in fact
install them - it just doesn't keep them on re-boot as you are running
from the CD and nothing gets installed to the HD.

Have had a few instances where the Broadcom chipset drivers install
fine when putting Ubuntu on but you also need to do the full Ubuntu
updates and a re-boot before the wireless card is active. After that
there's no problems connecting.

Also have an HP Pavilion....

Mine would not automatically download and install drivers for the broadcom wifi
device.

You need to find what broadcom device you have and search for the steps to get
it
working...it is a pain, but you should be able to get it going

I am a total nuub at Ubuntu, but I got mine going when I had it on my laptop

If you are running the Live disk then even if you are successful then it
will not stick. You are running from a RAM disk.

Setting up wireless is more complicated because you need to set up the
network with security as well. So it could appear to not work, but could be
not set up instead. Ethernet does not require this step so it would work
OTB.

One more point.

I have found that connecting to a wifi while in "try-Ubuntu" mode before
clicking the "install Ubuntu" icon will make updating while installing
work if you need to use a password or log into a network page to get
service. Once logged in a short interruption will not be a problem
because most networks have a timeout timer that keeps your computer
logged in.

Typically I try Ubuntu before I install because I can test the computer
for hardware that becomes a problem. If everything works in this mode
then installing while connected to the Internet has been little problem.
I also like to start the gparted editor and modify the hard-drive
manually before I start the install.

One more point. I like to have a wifi dongle with supported chipset
handy before I install. I don't have access to a LAN cable. Another way
is a 3G or 4G dongle works well. In the past they were somewhat of a
problem but not much anymore. If the 3G dongle fails to show a memory
device will show and un-mounting it uncovers the 3G device.

All in all my first experience with Ubuntu was a nightmare because of
unsupported WiFi, but today is only a minor inconvenience and only on a
few chip sets.

Just tried to install 12.04 LTS 32-bit on my HP Pavilion to get the links for my
broadcom
wifi....

It will not boot from it....not even to the try it screen.....locks up part way
through

I even downloaded and burned a new disk with the same results.....

Trying 11.04 shortly to see if it is my laptop or the software

I think it's a significant but rarely occurring problem with the 12.04
installation. I had the same problem with the 64 bit version on my
Gateway laptop. There is a way to get it started successfully and
download the drivers from within the new O/S. It involves interrupting
the grub process, changing something which will allow the system to
boot and then fixing it. Sorry I can't remember more but you should
find it with a search engine. I'm suffering from a severe case of
tendonitis in my leg at the moment and not really functioning very
well.

Sometimes burning a new disk is not a solution. There could be a problem
with the ISO in which case you should download a new one. If you are sure
that your ISO is good and the checksums work then there could be a problem
with your burning settings. Try burning at a slower speed (my usual
solution for such problems). Or it could be defective disks. Try a
different brand of disk. It could be one or several of these problems.

You could also try using the ISO to make a bootable usb thumbdrive. Use the
application, Unetbootin which is available for Linux and Windows, to
accomplish this.

Most likely it is a problem with the boot process and an incompatibility.
To troubleshoot you should press Esc as soon as the graphical boot screen
appears. This will put you in text mode and look at what is happening at
the time that it freezes and report back to us. You can override the boot
parameters to get around most issues.

You might try "nomodeset."

I *think* this is how to try it:
Hold shift from the BIOS boot to get a Grub menu. Press "e" on getting the Grub
menu. Using the arrow keys, navigate to, and delete, quiet and splash and type
the word nomodeset in their place. Press Ctrl-x to boot.

Only time I have had a machine lock up on install a trip to the bios and
turning off the unsupported equipment allowed the install to complete.
In my case it was the Wifi card but that may not be the offending equipment.

I might suggest turning of the wifi card first. If it still locks up try
turning the wifi back on and turn off the lan card.
continue in this fashion until Ubuntu installs. If nothing works then ...

You should be fine, once you install 12.04. I encountered the same issue when
checking 12.04 on my Pavilion. I did encounter an issue where the blue,
wireless light on the front would not come on, regardless of the position of the
wireless switch. I had to boot into Windows to get the light to come on, then
it would stay on when I booted to 12.04. That no longer happens.

If you create a "persistent USB drive," you should be able to install the driver
and have it work when you re-boot.

I've had good success using http://www.pendrivelinux.com/ to create a persistent
flash drive.