7 8
    1    1    0    0    0    0    0    0
    1   -1    0    0    1    0    0    0
    1    0    1    0    0    0    0    0
    1    2   -1    0    0    1    0    0
    1    0    0    1    0    0    0    0
    1    1    0   -1   -1    0    1    0
    1    0    0    0    0    0    0    1

4 5
    1    0    1    0    0
    1    1    0    0    0
    1   -1    0    1    0
    1    0    0    0    1

P Q R
3rd example

There was a (corrected) :
-------------------------------------------
Fault in Polyhedron_Scan
at DomainIntersection: 
  C1 =
call Polyhedron_Print(yyout, " %4d", C1)
POLYHEDRON Dimension:6
           Constraints:4  Equations:0  Rays:7  Lines:3
Constraints 4 8
Inequality: [    0    0    0  208 142380    1    0 ]
Inequality: [    0    0    0    0    0    1   -1 ]
Inequality: [    0    0    0    1    0    1    0 ]
Inequality: [    0    0    0    0    0    0    1 ]
Rays 7 8
Line:   [    1    0    0    0    0    0 ]
Line:   [    0    1    0    0    0    0 ]
Line:   [    0    0    1    0    0    0 ]
Ray:    [    0    0    0 35595  -52    0 ]
Ray:    [    0    0    0    0    1    0 ]
Ray:    [    0    0    0 -15820   23 15820 ]
Vertex: [    0    0    0 -15820   23 15820 ]/15820
call Polyhedron_Print(yyout, " %4d", D1)
POLYHEDRON Dimension:6
           Constraints:5  Equations:0  Rays:7  Lines:2
Constraints 5 8
Inequality: [    1    0    0    0    0    0    0 ]
Inequality: [   -1    0    0    1    0    0    0 ]
Inequality: [    1    0    0   -1    0    1    0 ]
Inequality: [    2    0    0    0    1    0    0 ]
Inequality: [    0    0    0    0    0    0    1 ]
Rays 7 8
Line:   [    0    1    0    0    0    0 ]
Line:   [    0    0    1    0    0    0 ]
Ray:    [    0    0    0    0    1    0 ]
Ray:    [    0    0    0    1    0    1 ]
Ray:    [    1    0    0    1   -2    0 ]
Vertex: [    0    0    0    0    0    0 ]/1
Ray:    [    0    0    0    0    0    1 ]

I suspect align_context...

call Polyhedron_Print(yyout, " %4d", C)
POLYHEDRON Dimension:3
           Constraints:4  Equations:0  Rays:4  Lines:0
Constraints 4 5
Inequality: [    0    1    0    0 ]
Inequality: [    1    0    0    0 ]
Inequality: [   -1    0    1    0 ]
Inequality: [    0    0    0    1 ]
Rays 4 5
Ray:    [    1    0    1 ]
Ray:    [    0    0    1 ]
Ray:    [    0    1    0 ]
Vertex: [    0    0    0 ]/1
stopped in Polyhedron_Scan at line 435 in file "erhart.c"
  435      C1  = align_context(C, dim2, MAXRAYS);
 print dim2
dim2 = 6
print n
`cca032041`align_context`n = 6
 call Matrix_Print(yyout, " %4d", M) 
4 8
    0    0    0    0    0    0    0    0
    0    0    0    0    0    0    0    0
    0    0    0    0    0    0    0    0
    0    0    0    0    0    0    0    0
stopped in align_context at line 393 in file "erhart.c"
  393         for (i=0; i<P->NbConstraints; i++)

