This Hadeeth is Saheeh (Authentic) and it was narrated by some senior scholars, such as Abu-Daawood, At-Tirmithi (Hasan (Sound)), Al-Haakim, Ad-Daarimi and Imaam Ahmad in several places in his Musnad.  It was also narrated by Ibn Maajah in his Sunan on the authority of ‘Aa’ishah . 

As mentioned, the Prophet, sallallaahu ‘alayhi wa sallam, said that that if any woman takes off her clothes in a place other than her husband's house, she has committed a great sin.

However, Al-Munaawi explained in his interpretation of this Hadeeth that taking off clothes applies only to a woman who does so before a non-Mahram (i.e., marriageable) man for unlawful purposes, such as prohibited sexual intercourse.  Certainly this does not apply to a woman who takes off her clothes before other women if her ‘Awrah (parts that she must cover according to Islam) is covered. 

Thus, it is not prohibited for a woman to take off her clothes in a closed room, an uninhabited house or in any other place, or before other women or Mahram men, provided that she covers all that must not be shown. In other words, she must cover her navel and knees and the area between them before women. As for Mahram men, a women is only permitted to uncover her head, arms and legs and cover all her body except her hands and feet before them.  

Allaah Knows best.