Guestbook Protection

hello everybody, I need some serious help.

somebody has "hacked" it isn't a hack actually, I think I know who it is and they classify EVERYTHING as hacking...

anyway somebody has flooded my guestbook and Its really annoying. it is made in flash and it writes to a txt file through php.

I want to make flash stop people from flooding. simple as that. If i make the text fields disappear thats just annoying because sometimes I double post...

hmmm i think i know how they flooded though so i'll fix that up... anyway i can make sure somebody doesn't post too many times in the same minute?
i know how new Date() works but I don't think that will work...