More computer issues

We have been battling virus after virus and fake-antispyware ater fake-antispyware and it just doesn't seem to get better for more than a week or 2. We are ok now, except we are completely banned from facebook now. Even if I try to get to facebook thru a search engine (which is another problem) it closes the internet connection and we are back to the desk top. The search engine (we usually use yahoo but this is happening on google too), doesn't matter what you search for, you click on what you want and are sent to some shotty second class search engine or to a shopping site. It is so irritating. I have run 3 different antivirus - malware - adware programs 6 times and even tho they have found things here and there, they haven't been able to catch what is going on with facebook and the search engines. grrrrrrrrr