spam filter

I have my internet Explorer homepage set to http://www.yahoo.com; why am I now getting a false "security" site

Instead of opening my browser to my homepage, http://www.yahoo.com, some kind of malicious software is changing my homepage to http://www.atotalsafety.com, and I am getting constant pop-up messages which try to get me to download security software (anti-spy, anti-adware, scans for spyware, spam protection, etc.). I have a very recent version of Norton Antivirus software installed and running, as well as the malicious software detection tool from Microsoft, but neither program is able to detect this malicious software described above. Has anyone else encountered this problem, and if so, how can it be resolved?

free scan and removal from Microsoft

http://safety.live.com/site/en-us/default.htm?s_cid=sah

How to detect invisible users on Yahoo! Messenger

Bitdefender Internet Security 2010 - 3 Pc/2 Yr [OLD VERSION] $0.01 The Industry's Best Value! BitDefender Internet Security 2010 provides 3 PCs 2 full years of protection against viruses, hackers, spam, and identity theft, without slowing them down. Includes: Firewall, Parental Control, Instant Messaging Encryption, File Vault (encrypts sensitive files), Laptop Mode (prolongs battery life), Gamer Mode, hourly updates and more. Provides 3 PCs 2 f...