Why does Yahoo allow some stranger to access my contacts and send offensive emails and then block me, the owne?

TRY THIS BEFORE CHANGING YOUR PASSWORD... NEW YAHOO! MAIL IS STILL UNSTABLE....IT WOULD BE BEST TO GO BACK TO YOUR PREVIOUS VERSION OF YAHOO! MAIL... To go back to YAHOO! MAIL CLASSIC... Turn off Javascript - you'll then be asked if you want to return to Mail Classic, click "yes". If you don't know how to turn off Javascript... For SAFARI: Open SETTINGS>click PREFERENCES>>click SECURITY>>Uncheck ENABLE JAVA and ENABLE JAVASCRIPT IMPORTANT:Remember to RE-ENABLE JAVA and JAVASCRIPTING back ON when you are back in Mail Classic because without it some mail functions won't work. For IE: Open TOOLS > INTERNET OPTIONS >> SECURITY. In security click "CUSTOM LEVEL" -> disable active scripting in the scripting section. IMPORTANT:Remember to turn JAVASCRIPTING back ON when you are back in Mail Classic because without it some mail functions won't work. For FIREFOX: Open TOOLS -> OPTIONS -> CONTENT, click on "DISABLE JAVASCRIPT". Now hit F5 to refresh the page while you are in Yahoo! email in order to switch back... In the options, click (PERMANENT) to switch back to YAHOO! Classic. DO NOT click the "ONE TIME ONLY" option. IMPORTANT: Turn JAVASCRIPT back ON once you have your "CLASSIC" account back. PLEASE ACKNOWLEDGE IF THIS SOLUTION WORKS BY CLICKING BEST ANSWER..THANKS