HAAR training hangs in 7th stage

Question

My Haar training gets hung in the 7th stage. Could someone please help to understand why and how I can get rid of such hung?

I use only 10 stages and have around 500 images.This is my training command:

opencv_traincascade -data data_50x50 -vec samples_50x50.vec -bg neg_70x70.dat -numPos 495 -numNeg 570 -numStages 10 -w 20 -h 20 -featureType HAAR -mode ALL -precalcValBufSize 1024 -precalcIdxBufSize 1024  -minHitRate 0.999 -maxFalseAlarmRate 0.1 -maxWeakCount 1000

Till 6th stage it runs fast (<5 hours), then in 7th stage, I am waiting days: I can see that FA is decreasing till 6th stage.

+----+---------+---------+
END>
Training until now has taken 0 days 0 hours 27 minutes 11 seconds.

===== TRAINING 6-stage =====
<BEGIN
POS count : consumed   495 : 495
NEG count : acceptanceRatio    570 : 1.59311e-06
Precalculation time: 4
+----+---------+---------+
|  N |    HR   |    FA   |
+----+---------+---------+
|   1|        1|        1|
+----+---------+---------+
|   2|        1|        1|
+----+---------+---------+
|   3|        1| 0.166667|
+----+---------+---------+
|   4|        1|        0|
+----+---------+---------+
END>
Training until now has taken 0 days 4 hours 2 minutes 32 seconds.

===== TRAINING 7-stage =====
<BEGIN
POS count : consumed   495 : 495

Remains in such stage for ages (>2 days)

Thanks