Dear All,
Thanks for info.
Nooluv, I checked my Zone Alarm - all boxes ticked but I remember doing this about 3 months ago. I've selected "ask" to see if this makes a difference. The problem is, Norton says I only have Symantec Redirector, IDS and Live Update installed. It used to say I had Anti-Virus definitions, too. I've not removed anything that I know of.
I've updated the definitions manually for the time being - I'll wait for the next prompt and see what happens.
Once again, thanks for all assistance.