To wrap this up, my desktop pc (tower, not laptop) is now AOK. Clock fixed, new CMOS battery did the deed. Motherboard bought August 2002 battery presumably then brandnew.
Understand that the EPROM needs battery power at boot. It certainly was not an in-out job --- done & switch on again 10 minutes after poweringdown --- as it restarted in Safe Mode with answers to difficult questions demanded (I settled for it loading defaults).
I post this to tell my readership the final result & to say thanx to respondents, 'tis what these Forums are all about. Bruce +++
Plz keep things simple. Age 77 displaying bad ping rate between brain cells
Windows XP Pro & W-Explorer with OEv6 & Asus A7V-333 & AMD XP2200 & Enermax 550watts & Leadtek GeForce T14200 & 1024 MB of PC2700DDR ram & 1394 Firewire & USB 1.1 plus 2 & Mirror Raid on two 60GB 7200rpm Barracuda & Aurigy2 PCI sound & Taxan 19-inch CRT monitor & Samsung internal read-only CD drive & LaCie external 48x12x48 CD burner & Epson Perfection 1200 scanner + negative copier & Netgear814 gateway & BT phone line & Zen Home ADSL2000 & Belkin phone-protect surgeblock & Excelsus filters & Firewall with AV & of course a sharp piece of string