In reply to climber david:
> when you say it only happens when you connect your phone via USB
This was only a half-baked theory based upon a single observation this morning TBH (I had been looking at pocket-lint.com for mobile phone reviews, then plugged in my phone whilst Chrome was closed, then opened pocket-lint.com and it had gone all crappy as described in the OP, which I assume is the mobile version)
> could it be tethering to the phone?
Possibly but it would be an odd thing to do, I think!
> Do you ever use your phone to access mobile internet and could it possibly be connecting through this. Had that cause me to end up at mobile sites before
Yes I do use my phone (in isolation!) to access mobile Internet.
I can only call it a vague/possible connection