Error messages such as "Login Failed", "This is a closed event you will need to request an invitation first" etc are displayed for very short time. They vanish before the user can read it.

Hi,

jomsocial using joomla system message for that. and any site template can using they own style for joomla system message.
if you using Protostar (joomla default template), you can see the different. that message disappear in shortly because site template that you using.

for increasing that system message time, please contact template provider for it.

Good Luck :)