Fatal error when connecting

I have installed the b5 version and played with it for a day.
All was fine yesterday, but today when I logged on I received a fatal error.
Only when I logged in from a different computer and logged out again, could I log on from the original computer.

The error code -

Fatal error: Uncaught exception 'FacebookRestClientException' with message 'Session key invalid or no longer valid' in /home/yossilac/public_html/fbtest/sites/all/modules/fbconnect/facebook-client/facebookapi_php5_restlib.php:1915 Stack trace: #0 /home/yossilac/public_html/fbtest/sites/all/modules/fbconnect/facebook-client/facebookapi_php5_restlib.php(379): FacebookRestClient->call_method('facebook.fql.qu...', Array) #1 /home/yossilac/public_html/fbtest/sites/all/modules/fbconnect/fbconnect.module(568): FacebookRestClient->fql_query('SELECT uid, nam...') #2 /home/yossilac/public_html/fbtest/sites/all/modules/fbconnect/fbconnect.module(193): fbconnect_get_connected_friends('577215455') #3 /home/yossilac/public_html/fbtest/sites/all/modules/fbconnect/fbconnect.module(176): fbconnect_block_render() #4 /home/yossilac/public_html/fbtest/includes/module.inc(450): fbconnect_block() #5 /home/yossilac/public_html/fbtest/modules/block/block.module(473): module_invoke() #6 /home/yossilac/public_html/fbtest/includes/theme.inc(1569): in /home/yossilac/public_html/fbtest/sites/all/modules/fbconnect/facebook-client/facebookapi_php5_restlib.php on line 1915