I am using dnn 07.01.02. In my site search is not working for announcement module. Also when i look at event viewer it doesn't show any error. When I first time search it doesn't show error. bt when i second time search it shows error.

A critical error has occurred. Unable to cast object of type 'System.Collections.Generic.List`1[System.String]' to type 'System.Collections.Generic.IList`1[avt.SearchBoost.Core.Search.SbFacet]'.

but its not showing error in event log viewer.