Fatal Execution Engine Error on the Windows2008 r2, IIS7.5

We are running some asp.net(3.5) applications on the Windows2008 r2, IIS7.5. Recently we got some event logs so difficult, we have not idea hope some guys can help.

1.EventID: 1334 (9-1-2011 8:41:57) Error message

An error occurred during a process host idle check. Exception: System.AccessViolationException Message: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. StackTrace: at System.Collections.Hashtable.GetEnumerator() at System.Web.Hosting.ApplicationManager.IsIdle() at System.Web.Hosting.ProcessHost.IsIdle()

2.EventID: 1023 (9-1-2011 19:44:02) Error message

.NET Runtime version 2.0.50727.4952 - Fatal Execution Engine Error (742B851A) (80131506)

3.EventID: 1000 (9-1-2011 19:44:03) Error message

Faulting application name: w3wp.exe, version: 7.5.7600.16385, time stamp: 0x4a5bcd2b Faulting module name: mscorwks.dll, version: 2.0.50727.4952, time stamp: 0x4bebd49a Exception code: 0xc0000005 Fault offset: 0x0000c262 Faulting process id: 0x%9 Faulting application start time: 0x%10 Faulting application path: %11 Faulting module path: %12 Report Id: %13

4.EventID: 5011 (9-1-2011 19:44:03) Error message

A process serving application pool 'AppPoolName' suffered a fatal communication error with the Windows Process Activation Service. The process id was '2552'. The data field contains the error number.

5.some info: we got the memory.hdmp(234MB) and minidump.mdmp(19.2) from control panel >> action center but I donot know how to use that :(

I think you need to deploy the debug tools. Please see these answers I posted regarding DebugDiag, ADPlus and WinDbg:

IIS problem, web application

CLR out Of Memory Exceptions

Tess Ferrandez's blog contains an Aladins Cave of methods and techniques to track down the cause of these sorts of problems.