Mac OS X infected by Malware

[FrankYang]

Hello,
My computer was infected by malware the day before yesterday(I suppose...) for downloading some apps online. And advertisements were full of the screen when I opened each website.
I used Avast and Symantec. They just worked out some problems. For example, they erase the advertisements. But until now there are still some tabs which will open automatically and some links, which direct to some unknown sources.
How can I solve the problem completely and safely?
Thank you very much!

 

[Jack]

Hello,
Can you please follow these steps:

1. From the Safari menu, select “Preferences“.
   
   
2. In the Safari Preferences window, click the “Extensions” tab. Find any unknown plugin, then click on the “Uninstall” button. This infection can add more than one extension, it is recommended that you remove all unknown extensions from Safari.
   
   

 

[FrankYang]

Yah, I've tried to do so but it doesn't work. When I moved my mouse to the unknown link, an mini-ad will appear with some small words like "ad by u1505", which is like MacVX. But I can't find any file(or safari extension) named u1505.

 

[FrankYang]

Hello,
Can you please follow these steps:

1. From the Safari menu, select “Preferences“.
   
   
2. In the Safari Preferences window, click the “Extensions” tab. Find any unknown plugin, then click on the “Uninstall” button. This infection can add more than one extension, it is recommended that you remove all unknown extensions from Safari.
   
   

Yah, I've tried to do so but it doesn't work. When I moved my mouse to the unknown link, an mini-ad will appear with some small words like "ad by u1505", which is like MacVX. But I can't find any file(or safari extension) named u1505.