Can you post a link to the page this is on? Sorry, I know you've posted it elsewhere, but I can't find it right now. Also, when you say "it started again", I don't know where else in this thread you mention this issue. Did you mean to post this in another thread?
As for the amount of invitations a user can send, it's decided by Facebook. The amount cannot be overridden, and it depends on a few different factors:
1) The user themselves (if they've invited other users already, if they seem 'spammy' with their invites on this or other sites, their number of friends, etc)
2) Your application (has a large number of invites already been sent, does the application seem spammy, how many users it currently has, etc)
There's nothing we can do about the actual max number that a user can invite, only tell Facebook that you'd like to allow a certain amount. Facebook then decides how many the user can really send.