Yes. Download the ISO. Burn it to disk or use Unetbootin (in the
repositories) or Startup Disk Creator to make a bootable USB stick. Then
when you reboot into the installer it will now check if you have the
previous version installed and offer to upgrade. I always do a clean
installation so have not used this myself. Always back up your data before
you upgrade. If you have a wireless connection then use Ethernet while you
upgrade and you can get updated packages while it installs. Getting it
wirelessly is iffy due to driver issues.

You can download the iso, then use the usb start up disk creater to stick it on
a usb stick. Run the live stick, then choose install, when it detects 11.04 on
the hardrive 1 option should be upgrade, just choose this option.

Don't forget to back stuff up first.

On the other problem I don't know anything that will be of use.

i would do a clean install from scratch, hav had problems with upgrades. also, i
would not ck off to do updates and 3rd party software, had 2 start over when i
tried that, as it wouldnt boot!

Most of the time I have seen the problem is I forgot to connect in
software. Take a look at the connection manager and make sure you are on
line. Do you have to sign in to the service to browse? If so don't
forget to sign in with the service firewall.

Issue 1. Evidently your 11.04 isn't standard any more ( and might be
related to issue 2 below ) so the upgrade cannot work. Trying to force
the upgrade will more than likely break Ubuntu so I'd recommend you do
not continue trying to do the upgrade to 11.10 - if you really want to
use it then a clean install is needed, with all that entails.

Issue 2. Amvis is a mail virus scanner and is pretty old, the last
'news' for it on Sourceforge was in 2004 !!! I'd suggest removing it
using Synaptic Package Manager and choosing the 'Complete Removal'
option. If you want to scan e-mail for viruses then there are up to
date packages that can do this but unless you are sharing e-mail with
Windows users then this really isn't necessary - the Windows user will
have their own AV scanner ( or at least, *should* have ).

When you say "continually," do you mean every five seconds or every five hours?

Do you have a mail server installed? A quick Google tells me that amavis is an
interface between a "mail transfer agent" and a virus scanner. You should be
able to remove it using Synaptic package manager.