First of all, if OneCare was installed and not activated, your friend is still basically protected. If it has dropped into expired mode, then some functions are unavailable, but protection is still available.
The key to this is that Help/About contains a subscription ID. If it has a subscription ID shown, it was activated. Further, if trying to activate returns an error that the product key has already been used, then it has. If there is a subscribe link in OneCare, then there should not be a subscription ID shown in Help/About *unless* the activation process failed.
So, let's do the following.
Go to http://billing.microsoft.com and sign in with the subscription ID you see under Help/About. Is there a OneCare subscription listed? Is it active?
Check the computer date and time. Is it correct? If not, change it and reboot.
Open OneCare and click Check for Updates. What happens?
What bothers me is that you describe two computers being in this state. Is there other security software on both PCs or was there and it was perhaps not completely removed prior to installing OneCare? That may be causing the subscription credentials from being updated correctly.
You may want to consider uninstalling OneCare from one PC and reinstalling it after confirming that no other security software is on the PC and that the date and time are correct. Then, click the subscribe link in OneCare and log in with the LiveID shown as the subscription ID. If that tells you that you need a subscription, but entering the product key tells you that the key has been used, you will need to contact support to determine what ID was used to activate the subscription.
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
-steve
