IIS上运行一段时间后提示：The 'OraOLEDB.Oracle' provider is not registered on the local mach

Question

请各位大神帮忙看看这个怎么解决，情况如下：项目部署到IIS运行OK，可是一段时间后就出现连接不了数据库，报错信息如下。
在IIS内点击回收或者重启IIS应用程序池就恢复正常，可是一段时间后又出现同样的错误。
System.InvalidOperationException: The 'OraOLEDB.Oracle' provider is not registered on the local machine.
   at System.Data.OleDb.OleDbServicesWrapper.GetDataSource(OleDbConnectionString constr, DataSourceWrapper& datasrcWrapper)
   at System.Data.OleDb.OleDbConnectionInternal..ctor(OleDbConnectionString constr, OleDbConnection connection)
   at System.Data.OleDb.OleDbConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningObject)
   at System.Data.ProviderBase.DbConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionFactory.CreateNonPooledConnection(DbConnection owningConnection, DbConnectionPoolGroup poolGroup, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionInternal.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory)
   at System.Data.OleDb.OleDbConnection.Open()
   at Inflor.Infra.Persistence.DataAccessControllerInternal.get_Connection()
   at Inflor.Infra.Persistence.DataAccessControllerInternal.PrepareCommand(OleDbCommand command)
   at Inflor.Infra.Persistence.DataAccessControllerInternal.FillDataTable(OleDbCommand command, String[] fieldsToTranslate)
   at Inflor.Infra.Persistence.DataAccessControllerInternal.Fill(OleDbCommand command, String[] fieldsToTranslate)
   at Inflor.Infra.Persistence.DataAccessControllerInternal.Fill(String query, String[] fieldsToTranslate)
   at Inflor.Infra.Persistence.DataAccessControllerInternal.Fill(String query)
   at Inflor.Infra.Persistence.DataAccessController.Fill(String query)
   at Seg.Service.NivelAcessoPagina(String pagina_path, String usuario)
   at SGF.Global.Application_AuthenticateRequest(Object sender, EventArgs e)
   at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step)
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Answer 1

IIS版本是7,
Framwork 是4.0

Answer 2

附上源码：
string connString = "Provider=OraOLEDB.Oracle;User ID=xxx;Password=xxxxData Source=(DESCRIPTION = (ADDRESS_LIST= (ADDRESS = (PROTOCOL = TCP)(HOST = XXXXX)(PORT = 1521))) (CONNECT_DATA = (SERVICE_NAME = MyDB)))";
OleDbConnection conn = new OleDbConnection(connString);
OleDbCommand cmd = conn.CreateCommand();
cmd.CommandText = sql;
conn.Open();

Answer 3

@版主，请帮忙分析分析呀。IIS上还有其他Application但是运行正常，就这个有问题。
每次有问题就只能手动回收Application Pool

Answer 4

每次都有调用conn.Dispose() 与 conn.Close() , 应该是关闭了的。
另外，如何确认连接池是否已满？