Need help have a install that about very 30 min or so will get this error over  a100 time then stop

AssemblyVersion: -1
PortalID: -1
PortalName:
UserID: -1
UserName:
ActiveTabID: -1
ActiveTabName:
RawURL:
AbsoluteURL:
AbsoluteURLReferrer:
UserAgent:
DefaultDataProvider:
ExceptionGUID:
InnerException: Value cannot be null. Parameter name: type
FileName:
FileLineNumber: -1
FileColumnNumber: -1
Method:
StackTrace:
Message: System.ArgumentNullException: Value cannot be null. Parameter name: type at System.Activator.CreateInstance(Type type, Boolean nonPublic) at DotNetNuke.Framework.Reflection.CreateObject(String TypeName, String CacheKey) at DotNetNuke.Services.Search.ModuleIndexer.GetModuleList(Int32 PortalID)
Source:
Server Name: WEBSERVER

Thanks
Fred Peacock