Actually we can not see why the did froze your account there are three typical reasons why they do that
Reason 1: Cash Out
Because of security reasons, PartyPoker is freezing everyones account the first time you are making a cash out. So when you make a cash out they will call you at the telephone numer given at the registration. If you were not available while they called you you can do two things. Write an email and tell them when and under which telephone number you are available. Then they will call you. Or you call them and tell them that you are available now and they will call you back.
As i said before this is mainly because of security reasons so they know that you are really the person that wants to cash out
Reason 2: Fake Account
When Party thinks you are the owner of more then one account they will freeze your account. Sometimes this happens when another person played from your pc with a different account. A telephone call like mentioned above will solve problems here too.
Reason 3: 5000 raked hands
You can only cash out after youve played 5.000 raked hands. This is because we provide you with the money to play poker and not to abuse our offer and simple cash the $50 we gave to you. So when you try to cash out before you played 5.000 raked hands your account will be frozen. Telephone call will help here too
But mainly it is reason 1.