Data Validation - Fix Errors & Make User Friendly

As a result of another Freelancer, my sign-up form appears to malfunctioning and I have no idea how to fix it. It works sometimes and other times it does not work at all. I'm looking for a developer who has worked on projects similar to this before and has a positive rating. There has been some script kiddies trying to inject malicious SQL injections into the site, the last developer tried to fix this but ended up making the form worse. The URL, IP and description is supposed to protect against these attacks but have caused various errors as a result. Whenever a user enters a new server, there will sometimes be a 500 error thrown and I can't figure it out. I have attached a screenshot of the form if that's helpful.