after the storms 2 weeks ago, the same happens to me.
my problem is pl, and there is nothing i can do about it.
here is what i recommend (what i did): First, download the freeware version of pingplotter. Second, trace any tribes 1 server. Third, most likely you will notice a PL hit within your ISPs network.
For example: I bounce off 3 hops before i leave my isp. From hop 3 to 4, i get pl, which of course shows throughout the rest of the trace.
After confirmation, call your ISP.