HelP me fast!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Hi, My Question is : Why People Can't Register on My Forum ? when they try to register It says "An Error Has Occurred!"
that is it, I Tried to much that they will get Registered, But they tried alot after i Post here to get solution , Any Solution Tell me Please

1. clear their browser cache
2. try using a different browser - IE etc
3. You 'join' them up for them. ask them for user name , email etc and then see if they can sign in, then they can change the password