PostgreSQL Error: server closed the connection unexpectedly

I cannot connect to PostgreSQL server from PgAdmin III , so I get this error: > Error connecting to the server: server closed the connection > unexpectedly > > This probably means the server terminated abnormally before or while > processing the request. I get the same error when I try connecting from psql. I have got this error 2 days ago but after restarting the computer the problem disappears , but this time I have restarted it too many times vainly. I'm using PostgreSQL 9.0.5 on windows 7 with ArcSDE 10.1 (Arcgis Spatial Database add-on), I have deactivated the antivirus and firewall. I have tried to reinstall PgSQL but the problem persists. How I can connect to my Pgsql service and get rid of this error?