It can happen quite easily Sorcha. I had to re-install Windows on my PC after installing an ADSL driver got me in a state where Windows would not re-boot no matter what I tried.

I tried to get other things working before installing my AV software and firewall. Something happened within the space of what at most can have only been 4 hrs. I became aware of a lot of modem activity and that when I switched the modem off, I was getting loads of 'redail' messages to enable sending stuff to all over the place. Whatever it was (and it can't have been something picked up from an email as I had no email set up - I was hacked in some way) also prevented me from installing my AV software.

I ended up with a 2nd re-install of the lot. This time round 1st thing I put on was AV and I got a firewall running and downloaded all MS "critical updates" ASAP.

I think the lesson learned is that you don't want to be leaving yourself unprotected even for minutes. There are swine out there who will get you if they can.

Jon