deggers,
assuming you have a wireless router then sounds like yours was a wireless interference problem (see my second reason)
Papigo,
You've not mentioned if you are wireless or not, which is why I've had to give you two options it could be.
But if it's is interference from the phone the reason your previous one didn't effect it is because new digital phones work in the 2.4Ghz range (same as wireless) older analogue cordless phones worked in the 900Mhz range, which is a long way from the wireless frequencies.