LINKSYS HG200 & ADSL connection problem

Can anybody offer some advice on this? I have bought a Linksys HG200 (the imfamous one sold in Tesco for a while) and it was in use with the previous owner for a year or so. Worked normally I'm told. I got it at factory default settings, got the menu up, settings for Tiscali entered & saved. It connected and worked wired/wirelessly with full encrytion and firewall for the whole weekend. Great I thought!
Turned it off overnight but when powered on it will not connect to the ADSL line? I have a flashing DSL LED and 3 others on, but no way will it be persuaded to connect. Tried it from within the menu, no deal. Tried saving & restarting this and/or the PC, no deal.
I have since done many full-resets, successfully updated to the latest firmware Linksys had for this model (June 2005?) another full reset... all to no avail :? The thing just refuses to work, despite having the same settings as it had when working! How can just turning it off (unplug PSU) affect the way it works when turned on? 8O
Anyone else had same problem? Any help will be most appreciated. Thanks in advance.