someone needs help with there kitty right now!!

Hi all
I belong to another cat club and this women posted this afternoon, cleary in a state of panic
hope some one can give her some advice
please read her message below
Please help! I am fairly new to this group and have enjoyed reading the messages. I am a real cat lover and have a major problem with my Harley. I need help and suggestions.
Harley is a little over a year old and has a biting problem. He suddenly comes out of nowhere and attacks ankles mostly and is gone in a shot. This is occasional, but even once is too much. He doesn't attack me anymore, but my husband and son are still his targets. A couple nights ago he nailed my husband, drew blood, and left all 4 fang marks on his leg. It's down to, a solution or his life.
I visited the vet yesterday and asked his advice. He said he was not a behaviorist, but said my options are limited. I asked about having something done to the 4 fangs that do the damage. He said it would dull them, but the biting would likely continue.
I have bought him every kind of toy I can think of to occupy his time and energy. The spray bottle just makes him mad and causes him to attack again. I had been the victim of his bites for a while, but we seemed to have worked our way through it. He likes to lay on my lap and purrs in delight.
My husband has warned that one more time and he's gone, one way or another. The last couple of days, I have shut him downstairs during the time my husband is in the house. He's out all day while my husband is at work. I can't keep doing this, but I don't want to take the chance that he will suddenly, and for no apparent reason, bite him on the ankle again.
Please help.

I can see that lady is in quite a bit of trouble with her cat, and I would also be quite worried if it happend to me.
I think the good news about what she wrote, is that the cat's behavior is something new, something which he didn't use to do and started all of a sudden. That sort of hints me that maybe something specific caused him to start doing it.
There could be a million reasons though.
She didn't mention if he is neutered for instance. If he isn't, maybe he's hormones are rushing in, and he's not being let out of the house. Many cats become surprinsingly agressive and even vindictive in such circumstances. I once tried to pet one of my (usually tame) cats when he was out at night on the balcony and he literally jumped on my face.
I'm can't help much here, but it also seems to me that maybe that lady's husband should give a hand out figuring what's happening and not just put her under the stress of controling the cat by closing him in the basement... I think it will just get the cat more frustrated.
Maybe another vet could also give her better advice... not being a behaviorist is a lame excuse from him.

Hope this can help somehow...