[PEDA] pb short-circuit beetwen pad and internal plane with protel 99se

[d-fabbro]

Hi,
I'm using protel 99se and for the third time since several years i have 
a serious problem
a via or pad with a label attached is abnormally connected to internal 
plane!!!
DRC is ok !!! and the via or pad being discussed is not visually in 
error ( color changing)
someone know the problem ? is there a solution!!?
thanks
excuse my bad english !!!