Internal Server Error

 We have  oracle report server forms and reports 10.1.2.0.2 I tried the following url and it display the page properly run and display below

http://172.16.2.79:7778/reports/rwservlet? 

When I tried the  run url: 

http://172.16.2.79:7778/reports/rwservlet/getjobid158?server=expapp_

it s running long time and after But I get the following error on the page.

 

Internal Server Error 

The server encountered an internal error or misconfiguration and was unable to complete your request. 

Please contact the server administrator, you@your.address and inform them of the time the error occurred, and anything you might have done that may have caused the error.