Persistent Bug - Warning: Singular matrix. Check node B

example :1 of 150 steps: .step tol=-25 vcc=70
2 of 150 steps: .step tol=0 vcc=70
3 of 150 steps: .step tol=25 vcc=70
4 of 150 steps: .step tol=-25 vcc=170
5 of 150 steps: .step tol=0 vcc=170
6 of 150 steps: .step tol=25 vcc=170
7 of 150 steps: .step tol=-25 vcc=270
8 of 150 steps: .step tol=0 vcc=270
9 of 150 steps: .step tol=25 vcc=270
10 of 150 steps: .step tol=-25 vcc=370
11 of 150 steps: .step tol=0 vcc=370
12 of 150 steps: .step tol=25 vcc=370
13 of 150 steps: .step tol=-25 vcc=470
14 of 150 steps: .step tol=0 vcc=470
15 of 150 steps: .step tol=25 vcc=470
16 of 150 steps: .step tol=-25 vcc=570
17 of 150 steps: .step tol=0 vcc=570
18 of 150 steps: .step tol=25 vcc=570
19 of 150 steps: .step tol=-25 vcc=670
20 of 150 steps: .step tol=0 vcc=670
21 of 150 steps: .step tol=25 vcc=670
22 of 150 steps: .step tol=-25 vcc=770
23 of 150 steps: .step tol=0 vcc=770
24 of 150 steps: .step tol=25 vcc=770
25 of 150 steps: .step tol=-25 vcc=870
26 of 150 steps: .step tol=0 vcc=870
27 of 150 steps: .step tol=25 vcc=870
28 of 150 steps: .step tol=-25 vcc=970
29 of 150 steps: .step tol=0 vcc=970
30 of 150 steps: .step tol=25 vcc=970
31 of 150 steps: .step tol=-25 vcc=1070
32 of 150 steps: .step tol=0 vcc=1070
33 of 150 steps: .step tol=25 vcc=1070
34 of 150 steps: .step tol=-25 vcc=1170
35 of 150 steps: .step tol=0 vcc=1170
36 of 150 steps: .step tol=25 vcc=1170
37 of 150 steps: .step tol=-25 vcc=1270
38 of 150 steps: .step tol=0 vcc=1270
39 of 150 steps: .step tol=25 vcc=1270
40 of 150 steps: .step tol=-25 vcc=1370
41 of 150 steps: .step tol=0 vcc=1370
42 of 150 steps: .step tol=25 vcc=1370
43 of 150 steps: .step tol=-25 vcc=1470
44 of 150 steps: .step tol=0 vcc=1470
45 of 150 steps: .step tol=25 vcc=1470
46 of 150 steps: .step tol=-25 vcc=1570
47 of 150 steps: .step tol=0 vcc=1570
48 of 150 steps: .step tol=25 vcc=1570
49 of 150 steps: .step tol=-25 vcc=1670
50 of 150 steps: .step tol=0 vcc=1670
51 of 150 steps: .step tol=25 vcc=1670
52 of 150 steps: .step tol=-25 vcc=1770
53 of 150 steps: .step tol=0 vcc=1770
54 of 150 steps: .step tol=25 vcc=1770
55 of 150 steps: .step tol=-25 vcc=1870
Warning: Singular matrix. Check nodes P2•X1 and B11•X1#BRANCH
56 of 150 steps: .step tol=0 vcc=1870
57 of 150 steps: .step tol=25 vcc=1870
58 of 150 steps: .step tol=-25 vcc=1970
59 of 150 steps: .step tol=0 vcc=1970
60 of 150 steps: .step tol=25 vcc=1970
61 of 150 steps: .step tol=-25 vcc=2070
62 of 150 steps: .step tol=0 vcc=2070
63 of 150 steps: .step tol=25 vcc=2070
64 of 150 steps: .step tol=-25 vcc=2170
65 of 150 steps: .step tol=0 vcc=2170
66 of 150 steps: .step tol=25 vcc=2170
67 of 150 steps: .step tol=-25 vcc=2270
68 of 150 steps: .step tol=0 vcc=2270
Warning: Singular matrix. Check nodes P2•X1 and B11•X1#BRANCH
Warning: Singular matrix. Check nodes P2•X1 and B11•X1#BRANCH
69 of 150 steps: .step tol=25 vcc=2270
70 of 150 steps: .step tol=-25 vcc=2370
71 of 150 steps: .step tol=0 vcc=2370
72 of 150 steps: .step tol=25 vcc=2370
73 of 150 steps: .step tol=-25 vcc=2470
74 of 150 steps: .step tol=0 vcc=2470
75 of 150 steps: .step tol=25 vcc=2470
76 of 150 steps: .step tol=-25 vcc=2570
77 of 150 steps: .step tol=0 vcc=2570
78 of 150 steps: .step tol=25 vcc=2570
79 of 150 steps: .step tol=-25 vcc=2670
80 of 150 steps: .step tol=0 vcc=2670
81 of 150 steps: .step tol=25 vcc=2670
82 of 150 steps: .step tol=-25 vcc=2770
83 of 150 steps: .step tol=0 vcc=2770
84 of 150 steps: .step tol=25 vcc=2770
85 of 150 steps: .step tol=-25 vcc=2870
86 of 150 steps: .step tol=0 vcc=2870
87 of 150 steps: .step tol=25 vcc=2870
Warning: Singular matrix. Check nodes P2•X1 and B11•X1#BRANCH
88 of 150 steps: .step tol=-25 vcc=2970
89 of 150 steps: .step tol=0 vcc=2970
90 of 150 steps: .step tol=25 vcc=2970
91 of 150 steps: .step tol=-25 vcc=3070
92 of 150 steps: .step tol=0 vcc=3070
93 of 150 steps: .step tol=25 vcc=3070
94 of 150 steps: .step tol=-25 vcc=3170
Warning: Singular matrix. Check nodes P2•X1 and B11•X1#BRANCH
95 of 150 steps: .step tol=0 vcc=3170
96 of 150 steps: .step tol=25 vcc=3170
97 of 150 steps: .step tol=-25 vcc=3270
98 of 150 steps: .step tol=0 vcc=3270
99 of 150 steps: .step tol=25 vcc=3270
100 of 150 steps: .step tol=-25 vcc=3370
101 of 150 steps: .step tol=0 vcc=3370
102 of 150 steps: .step tol=25 vcc=3370
103 of 150 steps: .step tol=-25 vcc=3470
104 of 150 steps: .step tol=0 vcc=3470
105 of 150 steps: .step tol=25 vcc=3470
106 of 150 steps: .step tol=-25 vcc=3570
107 of 150 steps: .step tol=0 vcc=3570
108 of 150 steps: .step tol=25 vcc=3570
109 of 150 steps: .step tol=-25 vcc=3670
110 of 150 steps: .step tol=0 vcc=3670
111 of 150 steps: .step tol=25 vcc=3670
112 of 150 steps: .step tol=-25 vcc=3770
113 of 150 steps: .step tol=0 vcc=3770
114 of 150 steps: .step tol=25 vcc=3770
115 of 150 steps: .step tol=-25 vcc=3870
116 of 150 steps: .step tol=0 vcc=3870
117 of 150 steps: .step tol=25 vcc=3870
118 of 150 steps: .step tol=-25 vcc=3970
119 of 150 steps: .step tol=0 vcc=3970
120 of 150 steps: .step tol=25 vcc=3970
121 of 150 steps: .step tol=-25 vcc=4070
122 of 150 steps: .step tol=0 vcc=4070
123 of 150 steps: .step tol=25 vcc=4070
124 of 150 steps: .step tol=-25 vcc=4170
125 of 150 steps: .step tol=0 vcc=4170
126 of 150 steps: .step tol=25 vcc=4170
127 of 150 steps: .step tol=-25 vcc=4270
128 of 150 steps: .step tol=0 vcc=4270
129 of 150 steps: .step tol=25 vcc=4270
130 of 150 steps: .step tol=-25 vcc=4370
131 of 150 steps: .step tol=0 vcc=4370
132 of 150 steps: .step tol=25 vcc=4370
Warning: Singular matrix. Check nodes P2•X1 and B11•X1#BRANCH
133 of 150 steps: .step tol=-25 vcc=4470
134 of 150 steps: .step tol=0 vcc=4470
135 of 150 steps: .step tol=25 vcc=4470
136 of 150 steps: .step tol=-25 vcc=4570
137 of 150 steps: .step tol=0 vcc=4570
138 of 150 steps: .step tol=25 vcc=4570
Warning: Singular matrix. Check nodes P1•X1 and B10•X1#BRANCH
139 of 150 steps: .step tol=-25 vcc=4670
140 of 150 steps: .step tol=0 vcc=4670
141 of 150 steps: .step tol=25 vcc=4670
142 of 150 steps: .step tol=-25 vcc=4770
143 of 150 steps: .step tol=0 vcc=4770
144 of 150 steps: .step tol=25 vcc=4770
Warning: Singular matrix. Check nodes P2•X1 and B10•X1#BRANCH
145 of 150 steps: .step tol=-25 vcc=4870
146 of 150 steps: .step tol=0 vcc=4870
147 of 150 steps: .step tol=25 vcc=4870
148 of 150 steps: .step tol=-25 vcc=4970
149 of 150 steps: .step tol=0 vcc=4970
150 of 150 steps: .step tol=25 vcc=4970
Warning: Singular matrix. Check nodes P2•X1 and B11•X1#BRANCH
Warning: Singular matrix. Check nodes P2•X1 and B11•X1#BRANCH
151 of 150 steps: .step tol=-25 vcc=5000
152 of 150 steps: .step tol=0 vcc=5000
153 of 150 steps: .step tol=25 vcc=5000
Warning: Singular matrix. Check nodes P2•X1 and B11•X1#BRANCH

Total elapsed time: 66.0943 seconds.