Just an update on the computer.

As of yesterday the IRP Hook Rootkit Trojan virus seems to have disappeared from the AVG scans - as others with the same problem found.
Here's hoping it really was just a 'false positive' and isn't lurking hidden on my computer.

This is the first potentially serious threat I've had (only been on broadband since Feb 2014) so I'm probably being a bit paranoid so thanks everyone for helping out. I can't afford to continually pay someone else to disinfect my computer - and a stuffed computer means no NT - now that really would be serious.

One can buy heating tape to wrap around the pipes where they
get exposed to the most cold. You plug it into electricity.

We have to use 2 each winter, and a heater downstairs besides!

Leaving a tap dribbling helps, but only "so much"... sometimes you need the heating tapes.

Thanks MrsD - I hadn't heard of heating tape.
Unfortunately my water pipe's buried underground where it runs from the water pump shed into the house - only a distance of about 4 yds but enough to freeze. Normally happens only a few days each winter - it's unusual to have 6 days in a row with sub-zero temps as we've had this past week (warmer but wetter today). The above ground section of pipe is insulated with lite density foam wrap.