IIS_WPG Permission disappears in the httpdocs folder in Plesk 8.6 with IIS 6.0

[axl]

Dear, please i need help ... this month happened to me 3 times that loses httpdocs folder permissions "IIS_WPG" on the Security tab of the folder, and my .aspx application this fall and have to grant permission again Plesk manually .... I have version 8.6 with IIS 6.0