The moments in which you are most vulnerable and when the probability of you making a mistake is great are associated with situations which search for solutions, especially based on collected information and documents. In this sign (and house) Mercury, by definition, has great power. Strangely enough, you are highly vulnerable in summarizing the available information and particularly in handling documents and tracing the logical connection between them. You are able to collect all sorts of facts, data, and the more they are, the more vulnerable you are to making bad decisions. It is difficult for you to filter out the important from the unimportant, to be practical. Therefore, it would be better to make decisions after discussing them with someone, in cooperation with someone else, preferably with a brother or sister.
     Mercury in Cancer (Fourth House)
     The moments in which you are most vulnerable and when the probability of you making a mistake is great are associated with situations that activate your emotional memory and provoke your feelings, regardless of whether they are associated with joy, excitement or sadness and sorrow. You are highly vulnerable when one of your emotional chords is hit, because you lose your ability to be logical, objective and rational. Personal attitudes are the biggest obstacle to correct decisions. It would be better if you do not make decisions when you are excited, feel sorry for someone/something or are ill-disposed. Talk to your mother or to a very close woman before making a decision.
     Mercury in Leo (Fifth House)
     The moments in which you are most vulnerable andwhen  the probability of you making a mistake is great are associated with the zeal to prove and express yourself, to shine. The ego is able to blur your correct judgment. You are also highly vulnerable when you find yourself in some romantic conditions, when Cupid's arrows fly toward you or someone compliments you, admires you or puts you on a pedestal. You have a strong creative intelligence which is driven when you are given the opportunity to shine, but it would be better to make decisions without other people’s interference - completely independently and regardless of how many compliments you have received, and if someone will admire you or not. Talk with your children (whether they are 3 or 30 years old).
     Mercury in Virgo (Sixth House)
     The moments in which you are most vulnerable and when the probability of you making a mistake is great are associated with the tendency to perfectionism and excessive criticism. In Virgo (the sixth house) Mercury, by definition, brings a lot of power that can easily be used and wasted in an unnecessary consideration for details. You are highly vulnerable to making mistakes when trying to make everything perfect down to the last detail. They say a small leak will sink a great ship. And for you, “fine-tuning” the small details can be the reason for you to make a mistake in the overall structure, i.e. to make a decision that is correct in terms of small matters, but is not regarding the final effect. It would be better to make decisions in a clean and tidy environment, to use tools such as a sheet of paper, pen or other, and to ask your colleagues.
     Mercury in Libra (Seventh House)
     The moments in which you are most vulnerable and when the probability of you making a mistake is great are associated with your aptitude for balance, harmony and equilibrium, and also when something beautiful stands in front of you, be it an object or person. You are highly vulnerable to beautiful things, to be liked in an attempt to be fair without affecting anyone. The more you think of how everyone can feel good the more you are open to wrong decisions. Life is often "unfair" and therefore whenever something has to be decided, someone will be affected. When making decisions, you should not be influenced by the external packaging, no matter how beautiful someone is or how shiny the object in front of you. The help of your spouse in your decisions is invaluable.