I'm told to update 95 files, but it says it can't download them

In your description no development utilities are shown.
This is an attempt to update and install the newest Linux kernel and is absolutely normal. In Ubuntu this cicle is almost every 2 months (without being scheduled)

As for the problem.. maybe a server problem ?
Try to change the server to main.
Open update-manager and click on "settings" and at the first tab (Ubuntu Software) you will see "Download From" , change that to :
main

Then try again to update - upgrade your packages.

sudo apt-get update
sudo apt-get dist-upgrade

Thanks

http://security.ubuntu.com/ubuntu/pool/main/l/linux/linux-libc-dev_3.2.0-36.57_i386.deb

error 404 file not found

there is no file like this on ubuntu server

The package linux-libc-dev_3.2.0-36.57_i386.deb is no more available on that server, because it has been superseded by newer versions (3.2.0-37.58, 3.2.0-38.59 and 3.2.0-38.60)

You have to reload your repository information to make sure that you are downloading the current packages.
Either use the 'Reload' button in one of the package management programs (update-manager, software-center, synaptic...) or open a terminal and issue the "sudo apt-get update" command.

Shortly after I logged in, Update Manager started and automatically listed items it considered necessary to update.

The setting s are already set to use Main and Universe, so that's not the cause of the problem.

That no development tools appear in the list given is merely because it was not shown in the failure dialog as it halted attempts when it failed to download even those few items out of 95 offered! The 95 items listed in Update Manager included features for developers as indicated by reading the description, so are of no use to me, plus software I do not need, such as MySQL. SO I need to know how to prevent those from appearing and cluttering up my system.

I'm only reporting what was shown in the dialogs. That a particular package is not available means that it should never have been offered via the Update Manager in the first place, so something is wrong there. The Update Manager automatically reads what is available every time it opens and should not need any background effort to update it.

I have managed to do most of what I need using apt-get update - but that has added all the 'junk' I don't want so will have to remove all that laboriously - which should not be necessary.

The standard installation of Ubuntu delivers a set of programs that are deemed appropriate for the majority of the users. There are some development tools included, because some packages need them. (e.g. If you install the driver delivered by Nvidia Corp. for a Nvidia video card, you need C compiler and dkms development tools that this driver's installation is possible).

I do not see a problem if I have some additional programs on my computer that I do not use. If there is a version upgrade for one of them there is no additional effort required, because it goes together with the update management process for the programs that I do use.

It seems to me that your original problem was caused by a time lag between reloading the repository information and executing the update command. You should regularly reload the repository information to make sure that you have up-to-date information about the current package versions.

I see a big problem with unused and unwanted software when you have limited disc space, as is the case with this machine! Hence the absolute need to minimise any unwanted and/or unused software.
For example, this is a desktop machine that is connected to a home network and thence a Brother laser printer and an ADSL modem/router. So why do I need drivers for HP printers? Why do I need files for 802.11g WiFi services? Answer is that I don't need them at all so I've had to remove them.
Similarly I have removed all unwanted language files, I am in the UK and exclusively use UK English so have no need or use of Australian English or US English dictionaries, etc. Likewise, I don't use any IM system ever so all those bits have been removed too. Plus I don't use any database applications, so don't need MySQL so that has been uninstalled as well.
I understand that some applications need various 'background' utilities but the Synaptic Package Manager helps show those dependencies so I don't remove essential files needed by applications I want to keep and use.
Having just performed the clean up operation I have been able to save 417 Mb of disc space added by the command line update and it feels more responsive - less extraneous data for it to sort through I guess.
I often wonder why developers assume everyone wants every bit of every available application. the machine is a tool to perform certain tasks. It needs only the software to enable those to be performed satisfactorily. Everything else is junk filling space that may be needed for actual useful functions.

As for regularly reloading update information, I understand that the Update Manager has that role and it automatically updates, or should. It then appears when there are updates available and I run it and try to perform the updates it offers after deselecting all the unwanted stuff. So there are no significant delays, just a few minutes really, between the dialog appearing and the update being attempted. So it must be up to date!
Are you really telling me that Update Manager does NOT update itself and it's list?? If so, why does it decide to appear and show that there are updates available?

Now I understand your reasoning. Ubuntu does not focus on disk space limitation, but on usability for the average user. So you really have to start tuning and slimming down your installation if you are extremely limited in disk space.

Just some hints to free additional disk space in case you do not know these:
- remove old kernels by purging all linux-image-... and linux-headers-... packages except the last one or two
- emptying the package management cache with the command "sudo apt-get clean"

My previous answer (#8) was to your message #6, this now is to #7:

You can set a parameter in the setting dialogue how often update-manager automatically reloads the repository information.
If there are updates waiting for installation, update-manager will pop up.
As far as I know these two things are more or less independent from each other. Update-manage, however, should tell you when it did a reload of the repository information the last time.

Hi Manfred
Thanks for the help.
Reply #8: That has saved a further 23% of the used disk space! Great, but why does it leave the outdated stuff behind?
Reply #9: Update Manager was already set to check daily, to display security updates immediately and other updates weekly. It is also set to show any new LTS versions. It seems, from the checks in response to #8, that it missed at least one kernel update!
In terms of what is an 'average' user, in my experience (I first used a computer in 1985 with CP/M) mainly on DOS, Windows and UNIX with a little bit of Apple flavouring for good measure, there is no such thing as a Mr or Mrs or Miss Average. There are users who have more intensive needs, such as developers and testers, those who have specific business needs, those who are experienced home users, those who are gamers and those who are interested in email but little else. In my case, this particular machine is used mainly for authoring and DTP with some email and access to internet for information gathering. So not at all like many users, hence different needs. That is why I need to select a different install set and why I suspect many are unhappy with some Linux systems as it is definitely less user friendly to maintain than is the case with some other OSs.

I suspect the Ubuntu development community have a different view but I'd like to see them take on board some of these comments and issues.