All connections, no matter what ISP will drop off from time to time. Its just a fact of life. I'm with Orange, and yes mine went off two days running last week. All I do is switch off the Livebox and switch it back on again. Then wait for the three light to stabilise. No need to run the CD again, that does nothing to the Livebox, it just installs the driver for your wireless adaptor.
I'm not sure what you mean by "no ordinary landline."
But it seems as though you may have a fault either with the line, the filter, or even the connection point on the wall. These can fail