Your last suggestion of disabling system restore, and re-enabling did the trick!
I would notice a loss in disk space very time I re-booted, but, I am now steady at 22.7 gigs after several re-boots! OK, so I was off with my estimated total, but I'm back in business!
Thanks Joe, erm, Phil me friend.
I've given up on Norton as I had to trouble-shoot it far too often, and for the time being am using AVG. A long term 'security suite' is what I'll seek eventually.
One last question before I head for PayPal is, should I compress my hard drive? I see the option there, but should I?
Thanks again me Worcestershire sauce merchant.