browser error or server

[rika]

every time i try to login with into an account i get this error
"HTTP Status 500 -

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

java.lang.NullPointerException

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.13 logs.
Apache Tomcat/6.0.13"

what can cause that since i did clean up i have this type of error on both firefox 9.0 and IE 8
also all other pages work fine could be a login problem ?

[Raymond]

It's the server problem.
HTTP Status 500 means "internal server error".