A process serving application pool suffered a fatal communication error with the Windows Process Activation Service.

Why does Application Pool Crashes Sometimes?
I was getting this error on my server

Log Name:      Application
Source:        Application Error
Date:          12/6/2011 3:57:47 PM
Event ID:      1000
Task Category: (100)
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      XXX
Description:
Faulting application name: w3wp.exe, version: 7.5.7601.17514, time stamp: 0x4ce7a5f8
Faulting module name: KERNELBASE.dll, version: 6.1.7601.17651, time stamp: 0x4e211319
Exception code: 0xe053534f
Fault offset: 0x0000b9bc
Faulting process id: 0x%9
Faulting application start time: 0x%10
Faulting application path: %11
Faulting module path: %12
Report Id: %13
Event Xml:

 
   
    1000
    2
    100
    0x80000000000000
   
    73326
    Application
    XXX
   
 
 
    w3wp.exe
    7.5.7601.17514
    4ce7a5f8
    KERNELBASE.dll
    6.1.7601.17651
    4e211319
    e053534f
    0000b9bc
 

and after this i usually get an error


"A process serving application pool 'XXX' suffered a fatal communication error with the Windows Process Activation Service. The process id was '1234'. The data field contains the error number."





I am running an ASP.NET Framework 3.5 under integrated environment web application on IIS 7.5 on Windows Server 2008 R2.Sometimes i get this error  When access to the website, it raise error message: ‘HTTP Error 503. The service is unavailable.’.

I am still working on this issue and got some temporary measures that delay this error
measures taken under Application pool advanced settings changed the settings :
1)   Maximum worker processes to 2 and made it a Web Garden
2)  Changed the Rapid failed protection Failure interval to 2
3)  And lastly changed the Recycling regular time interval from 1740 (default) to 1000.

since that time its working properly but for a quick measure when you are facing this issue
 go to the Internet Information Services (IIS) Manager to recycle my Application Pool again. it would work properly .