On a similar vein, I had trouble with the Wi-Fi connection to my printer a few months ago.
I would try to scan a picture or document from my printer, to my picture library on my laptop. Sometimes it would work, sometimes not.
As I had a 3yr replace with new insurance with PC World, I took my printer back. They replaced without any problem and threw in two packs of printer cartridges.
However on setting up said new printer, I was experiencing exactly the same problem!
Living in Hull we are on the 'Kingston Communications' phone system with Karoo, so one phone call later, (after trying to understand the over the phone techi person, explaining what I should do) the engineer arrives.
He replaces the 'Router' with an up to date version (the one we had, they installed 18mths ago) and 'Voila' exactly the same problem.
After several cups of our coffee, he pulls out some sort of meter/gizmo, and walks around the room turning electrical items off and on.
Turns out our mini radio/cd player which is situated between me and my laptop, and the printer across the room is interfering with the signal when it is switched on. So I have to either have said radio/cd player switched off when using laptop/printer, or move the radio to a position that doesn't interfere with the signal. We moved the guilty item across the room and have had no more problems since.
The thing I don't understand is, everything had worked fine for the last 18mths !!!!!!!
Ain't modern technology wonderful (not)
Gregg