Thanks all for your help. When I got home my new SVD and new IMR
batteries were waiting for me. First charge on one of the new IMR's caused the same problem. One multimeter later, I have ascertained that the charger wasn't doing my
batteries any good. Managed to fry the second battery after leaving on charge overnight about a week later. Now I am stuck at work, chewing gum and waiting for my hot wife to post the new charger and battery out. Bugger it. Good news is that the old SVD was still working, but the switch is now on the way out...