I finally got rid of the malware residing in the system with the help from one of the people here. And I thought everything was now okay until my sister pointed out two things:
1. She can't log-in to Friendster
2. Even when she log-off from Yahoo and clicked "REturn to Yahoo mail", instead of the Log-in it is her mailbox being displayed.
What I had been doing were:
1. regsvr32 urlmon.dll on the Run command and click OK then did the same with