The company had previously announced that a significant one-off profit of from a long-term contract would offset lower than originally expected profitability follow the conclusion of several contracts.
Now, however, it has been discovered that the one-off gain was miscalculated by £4.3.m, meaning that profits will once again take a hit for the year to 31 July 2011.
As part of the year-end audit process, new finance director Rod Harris, who joined in June from Carillion Business Services, has reviewed contract risks and project claims. As a result, the group has decided to increase provisions against these contract risks and project claims by a further £4.3m.
The reduction in the one-off gain and the increase in provisions relate to non-recurring and non-cash items.
Mr Cuthbert tendered his resignation with immediate effect. Chairman Bo Lerenius will stand in as executive Chairman until a new chief executive is appointed.
Mr Lerenius said: "I would like to express the board's gratitude to Rich for his many years of service and his continuing belief in and commitment to the business. The board will focus on maintaining Mouchel's position in its core markets in the interests of all its stakeholders."
