I've got the triangle with exclamation sign inside in system tray, description is the following :
The update information is outdated. This may be caused by network problems or by a repository that is no longer available. Please update manually by clicking on this icon and then selecting 'Check for updates' and check if some of the listed repositories fail.
'Check' updates doesn't help - it shows no updates everytime. It would be greatful if somebody could help me to solve it