Thomson TG585 v7 and Windows 7

[#1]

The only thing I can suggest is that something on the motherboard wasn't right when it shut down normally but pulling the plug when it was powered up caused it to reset itself.
Why or indeed how this could mess up the router I have no idea unless something was saturating the router connection to the network possibly related to the network card in the PC

[#2]

OldJim.
As I mentioned earlier I am  about as useful as a chocolate teapot when it come to technical stuff. I only bought new pc as my previous one was 6 yrs old and Arthur Neagus was asking if he could have it..lol
MANY thanks for yours and Peters Help. At least i know where to come if I have issues in the future 

[#3]

Since the only direct electrical connection between the PC and the router is the ethernet cable  - could it be faulty in some way?
If you have a spare cable, it could be worth giving it a try.