yesterday i downloaded the openerp version 7.0 and i worked on it for almost 2-3 hours

today when i entered my username and pwd i got the following error

Your version of OpenERP is unsupported. Support & maintenance services are available here: OpenERP Entreprise.
OpenERP Server Error
Client Traceback (most recent call last):
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\openerp\addons\web\common\http.py", line 180, in dispatch
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\openerp\addons\web\controllers\main.py", line 498, in authenticate
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\openerp\addons\web\common\session.py", line 73, in authenticate
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\openerp\addons\web\common\openerplib\main.py", line 117, in proxy
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\openerp\addons\web\common\http.py", line 608, in send


Server Traceback (most recent call last):
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\openerp\addons\web\common\http.py", line 593, in send
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\.\openerp\netsvc.py", line 360, in dispatch_rpc
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\.\openerp\service\web_services.py", line 397, in dispatch
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\.\openerp\service\web_services.py", line 408, in exp_authenticate
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\.\openerp\pooler.py", line 50, in get_pool
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\.\openerp\pooler.py", line 33, in get_db_and_pool
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\.\openerp\modules\registry.py", line 180, in get
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\.\openerp\modules\registry.py", line 192, in new
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\.\openerp\modules\registry.py", line 67, in __init__
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\.\openerp\modules\db.py", line 143, in has_unaccent
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\.\openerp\sql_db.py", line 152, in wrapper
  File "C:\Program Files\OpenERP 6.1-20120821-233337\Server\server\.\openerp\sql_db.py", line 212, in execute
OperationalError: server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.

thanks in advance