I’m constantly receiving the 0x800XXX69 error and my account is blocked!

I'm using Outlook Express in order to send and receive e-mails.

A few days ago, I received the following error for the first time:

Server: 'smtp.live.com', Protocol: SMTP, Server Response: '550 5.3.4 Requested action not taken; We noticed some unusual activity in your Hotmail account. To help protect you, we've temporarily blocked your account.', Port: 25, Secure port(SSL): Yes, Server Error: 550, Error Number: 0x800CCC69.

I tried to log-in through a browser and after typing my password, I got a message that my Account is temporarily blocked and I have to verify it.

So, I verified it by sending an sms on my mobile. I have been asked to change my password and then everything was on place again. I started sending/receiving e-mails again.

This kept for two days. Then the account has again been blocked and I received the same message again. 

I did the same procedures and the account has been released for another 2 days. 

This happened 4-5 times 'till today, that I changed again the password and re-activated my account.

This e-mail account is used only by me and the maximum number of e-mails sent daily is 15. Of course, they have nothing to do with spamming.

But, usually I send 5-10 e-mails daily.

Do you have any idea which my problem might be? How can I solve this issue???

I have tried from different ISP's and again I'm getting the same results. It seems that something goes wrong with my account.

Thanks in advance for your help,

Best Regards,

Constantine