Subversion reported an error

Hi
I am svn adminstator and using svn verion 1.6 it is on linux
actually there is total 4 repositories in svn, i can access 3 repository (I can perform svn admin work)
but for one repository Acces to '[repository_Name]!svn/ver 488519' forbidden.
it is suddenly happening.
i will really appriciete if some one help me asap.

Moderator comments were removed during original forum migration.

Sorry i am new user to this group i don't know how to post image here.
please explain me.
as a svn administrator when i am trying to delete or create some folder form specific repository it is giving me access forbidden and It is happening suddenly .

please help me ASAP i really appreciate your help.

Posting an image is exactly what we don't want.

Copy paste the error text and the context.

following error is having while perform any svn admin work

Access to '/ij/!svn/ver/537023' forbidden

Access to '/ij/!svn/ver/537023' forbidden
in the same svn application there are other more 4 repository and i am able to perform svn admn duties for those repository using same svn admin credentials.

And what command provoked that error?