Browser sends multiple request 5 to 10 request in a second withoutuser action

Our application is created in C#, ASP.Net 2.0, SQL 2005; the session
is managed in SQL server with ASPState. We often file below exception

Error Details :

Exception of type 'System.Web.HttpException' was thrown.

Source : System.Web

Stack Information : at System.Web.HttpAsyncResult.End() at
System.Web.SessionState.SessionStateModule.EndAcquireState(IAsyncResult
ar) at
System.Web.HttpApplication.AsyncEventExecutionStep.OnAsyncEventCompletion(IAsyncResult
ar)

Inner Exception : System.Web.HttpException: Unable to connect to SQL
Server session database. ---> System.InvalidOperationException:
Timeout expired. The timeout period elapsed prior to obtaining a
connection from the pool. This may have occurred because all pooled
connections were in use and max pool size was reached. at
System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection
owningConnection) at
System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection
outerConnection, DbConnectionFactory connectionFactory) at
System.Data.SqlClient.SqlConnection.Open() at
System.Web.SessionState.SqlSessionStateStore.SqlStateConnection..ctor(SqlPartitionInfo
sqlPartitionInfo) --- End of inner exception stack trace --- at
System.Web.SessionState.SqlSessionStateStore.ThrowSqlConnectionException(SqlConnection
conn, Exception e) at
System.Web.SessionState.SqlSessionStateStore.SqlStateConnection..ctor(SqlPartitionInfo
sqlPartitionInfo) at
System.Web.SessionState.SqlSessionStateStore.GetConnection(String id,
Boolean& usePooling) at
System.Web.SessionState.SqlSessionStateStore.DoGet(HttpContext
context, String id, Boolean getExclusive, Boolean& locked, TimeSpan&
lockAge, Object& lockId, SessionStateActions& actionFlags) at
System.Web.SessionState.SqlSessionStateStore.GetItemExclusive(HttpContext
context, String id, Boolean& locked, TimeSpan& lockAge, Object&
lockId, SessionStateActions& actionFlags) at
System.Web.SessionState.SessionStateModule.GetSessionStateItem() at
System.Web.SessionState.SessionStateModule.PollLockedSessionCallback(Object
state)

Target Site : System.Object End()


The wondering thing here is these exceptions are just flooding in from
the cleint while they request the application via browser and time it
go on and on for 30 minutes, please do any one has any clue or faced
such issue in past, we were looking at the solution but not able to
find any.

Thanks in advance.
H Patel