Upgrade onereic

[Roger]

Hi all
I have a standard desktop pc.
I've been trying to upgrade Oneiric to Precise using the upgrade tool 
which advises that 12.04 LTS is available
I click on the Upgrade button, it downloads the Release Upgrade Tool , 2 
apps, then nothing happens., Ive waited 10 minutes watching the System 
Monitor and there is no internet activity.

My daughter upgraded her laptop easily on Saturday evening but I have no 
luck.

Any suggestions on how to proceed the upgrade are most welcome.
thanks
roger