Siegeory: Hi, thanks for your reply.
There is only 3 jack points in the house, 2 that are in use and have filters on them.
I might be able to test another modem later tonight, just to see if it's the modem.
Thanks,
Chris.
Try unplugging everything (phones, filters, Sky, etc.) except the modem from the jacks; then try the modem in each jack.