This was the error, i recieved recently when i open an Excel sheet in browser.  I didn’t recived this error before, so i searched in recent log file. That file list out the following line

03/04/2009 14:27:33.07    w3wp.exe (0x14C4)    0x020C     Excel Services      Excel Services Web Front End  5pad    Critical     No Excel Calculation Services is available in the farm.[User: SHAREPOINTsystem]

Then i understood, there is no Excel Calculation Services available in my Server Farm. So, I moved to my Central Administration Page,

  • Central Administration -> Operations -> Services on Server 
  •  Select Excel Calculation server role radio button
  • Start the Excel Calaculation Services

Now I moved back to my Excel sheets Library and clicked the Excel File. Now all works fine for me…