Sync error due to "very light ground"?

[#1]

Not related to a PlusNet connection, but has anyone ever heard of a "very light ground" fault on a telephone line?
I've googled and googled and cannot find any mention of it, even though apparently its causing a lack of ADSL sync. I thought "i know, i'll ask my ISP and see if they've heard of it!"
Am tearing my hair out on this one - usual story.. ISP blames telco provider, Telco provider blames ISP (and say they've never heard of a "very light ground" fault) and its my lot today to try and get it sorted once and for all 
Regards,
Ashley

[#2]

The incoming BT cable consists of two wires -
White 'A' wire (0V to earth)
and
Orange 'B' wire (-50V to earth)
My guess is that "very light ground" probably means that both wires are floating (in voltage) a little more than is usual, away from the intended 0V earth.
This would suggest that somewhere along the line that the resistance to earth is degrading (i.e. increasing), or an earthing point has fallen off at the exchange (or possibly at the roadside cabinet).
Having effectively floating phone wires will almost certainly make the broadband connection MUCH more susceptible to interference, and as a result cause sync losses.

[#3]

"Ground" is more often used in the US and refers to what is normally called "earth" in Europe. A fault like yours means a high-resistance earth fault somewhere along the line, which probably means that insulation is degrading somewhere and effecting the (all-too vulnerable) voltages imposed on the phone line and inducing a fault condition. This in turn will affect the ability of your line to carry data properly.
Roll on fibre!

[#4]

Speaking of earths; I'm awaiting my broadband installation and in the process had a BT engineer round to check the line etc.
I was somewhat surprised to find him attempt to obtain a reference earth for his test equipment from one of the tails of my radiators... which considering the very-evident plastic plumbing and (not-so-evident) timber frame house was unlikely to offer much, if any, earthing!
I queried the validity of his approach but he carried on regardless. Only when his tests repeatedly failed did he then reluctantly make up a cable to use the earth from a plug socket and everything worked out fine. Not wishing to knock him personally as he came up trumps in the end but it did make me wonder what effects this may have had in other instances if things like this are not a part of standard training!
Mathew

[#5]

Thank you all, especially purleigh.
Looks like the fault got fixed in the end, hopefully for good.
Thanks again,
Ashley

[#6]

I have a 40 Plus old installation and originally had a bare copper wire to an outside ground spike, which is still there but not connected