NIS 2012 thinking it's not up to date?

I had two unusual things happen today with NIS 2012 (currently showing 19.7.1.5). (Using Windows 7 64-bit)

 

First, when I booted the computer the icon in the system tray showed an error state. When I opened the program, it said it needed to do a scan, even though I did a full system scan 6 days ago. I run a full system scan regularly once a week and this has never happened before, so what might have been going on? Anyway, this time I did a quick scan, which cleared the error state, but isn't NIS supposed to run its own quick scans on a regular basis? Looking in my history, it seems like the last quick scan was about 9 days ago.

 

Secondly, shortly afterwards, following my normal pattern, I did a manual live update and was shocked to find that I needed to download 153MB of updates. From another thread, I gather this may have been the full virus database, and as the computer didn't need a restart afterwards, I think this probably will be the case. Again, this hasn't happened before, so what was going on today? I'm particularly concerned about this as I'm on metered broadband, and too many downloads of this size will take me over the limit.

 

Another identical computer in the household, which is also booted afresh each day and has a manual live update before doing anything else, was completely normal and didn't experience either of these issues.

 

The only things I'm aware of that have changed recently are (a) I entered a new product key about 3 days ago for another year's subscription; and (b) yesterday both computers had an unusual warning message in the Windows log about a possible memory leak in Application (C:\Windows\System32\svchost.exe -k LocalServiceNetworkRestricted) - this was around the time they were doing the live update, so I'd wondered if this might be connected. (However, as I said, the other computer was normal today; and there have been no Windows error messages on this computer today.)

 

Please can anyone suggest what might have been happening, and any settings etc that I might need to check?

 

Thanks.