I have this problem right now. I have called Paypal multiple times. Here is what I know.
I was not able to send 3$ as a gift, but I could as goods. So if you are trying to send as a gift try sending as goods.
Also, since you have not used your Paypal account much, they are flagging people for unusual activity. So if you haven't used it in a while then they are going to be heavy on security with your account.
Next, are you in a different location then where you made the PP? Or do you have say a Canadian PP but live in Australia? This can sometimes make it difficult.
When I had this problem I called PP and had to talk to a high level security customer rep who had to go in and look at why it was doing it. Took about 6 calls before someone connected me to her but she got it figured out. Then one week later it did it again.
TLDR; call Paypal