Good day I am using Ubuntu Studio 12.04 and find that even after reconfiguring it in the last week updating causes program download errors.

Before reconfiguring it was not working, now after applying updates I get this:

Failed to fetch http://security.ubuntu.com/ubuntu/po...204.1_i386.deb 404 Not Found
Failed to fetch http://security.ubuntu.com/ubuntu/po...204.1_i386.deb 404 Not Found
Failed to fetch http://security.ubuntu.com/ubuntu/po...1204.1_all.deb 404 Not Found

What can I do, reconfigure and never install updates, never bank on this computer?

Please be more specific:
- What did you reconfigure?
- What were the problems before rconfiguring?
- How exactly did you update the system?

I reconfigured my Dell desktop hardrive.
Ubuntu Studio worked, until I installed updates as the icon on the top right as it automatically reminds the user. After that, there were problems installing new software. It would start to install then pop up a problem warning, I think it was about dependancies, it would never download and install.
I re-installed Ubuntu Studio 12.04, which is alike Xubuntu. I Installed all the updates as advised by the automatic update icon again, top right, an exclamation mark. From then on, no programs install from the software centre.

Please post the output of

part of update:
42 B]
Hit http://security.ubuntu.com precise-security/main TranslationIndex
Hit http://security.ubuntu.com precise-security/multiverse TranslationIndex
Hit http://security.ubuntu.com precise-security/restricted TranslationIndex
Hit http://security.ubuntu.com precise-security/universe TranslationIndex
Hit http://security.ubuntu.com precise-security/main Translation-en
Hit http://security.ubuntu.com precise-security/multiverse Translation-en
Hit http://security.ubuntu.com precise-security/restricted Translation-en
Hit http://security.ubuntu.com precise-security/universe Translation-en
Get:15 http://au.archive.ubuntu.com precise-updates/universe Sources [101 kB]
Get:16 http://au.archive.ubuntu.com precise-updates/multiverse Sources [8,468 B]
Get:17 http://au.archive.ubuntu.com precise-updates/main i386 Packages [747 kB]
Get:18 http://au.archive.ubuntu.com precise-updates/restricted i386 Packages [11.5 kB]
Get:19 http://au.archive.ubuntu.com precise-updates/universe i386 Packages [230 kB]
Get:20 http://au.archive.ubuntu.com precise-updates/multiverse i386 Packages [14.4 kB]
Hit http://au.archive.ubuntu.com precise-updates/main TranslationIndex
Hit http://au.archive.ubuntu.com precise-updates/multiverse TranslationIndex
Hit http://au.archive.ubuntu.com precise-updates/restricted TranslationIndex
Hit http://au.archive.ubuntu.com precise-updates/universe TranslationIndex
Hit http://au.archive.ubuntu.com precise-backports/main Sources
Hit http://au.archive.ubuntu.com precise-backports/restricted Sources
Hit http://au.archive.ubuntu.com precise-backports/universe Sources
Hit http://au.archive.ubuntu.com precise-backports/multiverse Sources
Hit http://au.archive.ubuntu.com precise-backports/main i386 Packages
Hit http://au.archive.ubuntu.com precise-backports/restricted i386 Packages
Hit http://au.archive.ubuntu.com precise-backports/universe i386 Packages
Hit http://au.archive.ubuntu.com precise-backports/multiverse i386 Packages
100% [Waiting for headers]

brendan@brendan-Inspiron-410:~$ sudo apt-get upgrade
[sudo] password for brendan:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages have been kept back:
linux-headers-lowlatency-pae linux-image-lowlatency-pae linux-lowlatency-pae
The following packages will be upgraded:
linux-libc-dev
1 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.
Need to get 860 kB of archives.
After this operation, 2,048 B of additional disk space will be used.
Do you want to continue [Y/n]?

pop up looks like this: "i" in a blue circle, and "software updates available".

After doing this, it seems to be working again, what, exactly went wrong?

I can't say, since there is no error message on the command line.