Keeps blocking IPs + words

Unsure why, but i need assistance in it keeps blocking Odd things.
First it blocked someone searching for the word VEGA
then it blocked someone whom i can confirm is now on a certain IP blacklist thanks to being marked as spam on here. – yet i cant ascertain why it was marked as spam in teh first place. – i believe this also happened after the user was able to get in sign up then it started blocking them from using the sites functions.