As suggested I've just downloaded and installed AVG anti-virus software v 7. Working fine. I seem to have another anti-virus software on my pc - PC cillin 2000. Think this was a free one at the time but i've never updated it as far as I can remember. Is the best idea just to uninstall PC cillin and stick with AVG?

Yes, from a Hijack This log you posted, you are running PC-Cillin 2000 which is a very old version of the PC-Cillin software and I believe it may be unsupported by Trend Micro and your subscription may have run out. Uninstall it and stick with AVG, its a brilliant program.

Thanks for answer Owen.
However when I came to uninstall it - it gives me a message ' Fatal error during installation' and still appears in the list of programs.
Any ideas?

Also with AVG can I temporarily 'disable' it if I choose to? Someone has suggested this may be causing the issues I'm having with iTunes and that I should disable it whilst importing CDs. Right clicking doesn't appear to be giving me the option.
Cheers for help

You will need to quit the Control Centre by right clicking it in the System Tray and selecting Quit AVG Control Center. Then restart it via the Start> Programs menu afterwards.

Have a read of this info for uninstalling PC-Cillin 2000 manually if the uninstallation continues to fail.

Thanks for the help, but the icon is no longer in system tray!
I can't access either through start menu either it says - IOT_Initializedeviceandscanengine error code = 2.
any ideas how I can now get rid?! it appears some of it must be uninstalled but some is still there!
cheers as always

Owen's advice was for closing down AVG Anti-Virus temporarily to see if iTunes works, not for closing down PC-Cillin.

If you're having trouble uninstalling PC-Cillin still, did you follow the advice in the link that Owen gave you?

Sorry my reply was to do with following the instructions which Owen posted the link to for uninstalling pccillin!
It also starts with 'Right-click the PC-cillin icon on the system tray'. Which isn't there and I get that error message when trying to load up through 'start' menu.
Any ideas?

Well that shows the majority of files have gone if its not in the System Tray. That advice about using the Start menu uninstall option is if the uninstaller is working correctly, in your case it isn't. You need to scroll down to the Manual Removal bit and follow those manual instructions.