Locked Out! Despite Having The Right Password!

Help!

All of a sudden I can no longer login to my Admin account.

I get an error message to the effect that account have been locked out
due to 3 unsuccessful attempts.

Several hours later I try again and I was able to get in except that I
got another message to the effect that the security log is full. I
emptied the security log and created another admin account.

I'm still finding a problem logging in with both of them.

Any idea as to how can this happen and also how do I resolve it.

Thank you very much

Mike