Weird Computer/cellphone issues

Not sure what to do about this:

A couple nights ago I was working on the computer and it suddenly shut down completely out of nowhere with a black screen I'd never seen before. It took quite a lot for it to boot back up when I tried.

Then the next day I was applying for a job online and when I went to click on a link the website wouldn't pop up...the tabs that were opened were ADT home security and one other, don't remember what it was.

I checked and the business checks out as well as the other website I was trying to click on.

The next morning I got a text message on my phone from a number I don't have in my phone, with a contact name that is written as an email address. How could I have someone's contact as their text message name without having them in my contacts at all? Also the message is obviously spam(claim your prize, etc.)

To top it all off...my computer has been really slow lately.

I ran avast and malwarebytes and nothing has shown up but I know something is going on.

Also a few days ago I had something pop up about using windows defender to get rid of something on my computer...I'd never seen or heard of windows defender before that. I also have dealply on my computer...it's been there for a while, actually. Not sure how it got on my computer though but I don't know how to get it off either.

What should I do?

 

computer:

http://housecall.trendmicro.com/uk/index.html

http://www.microsoft.com/security/scanner/en-gb/default.aspx

phone:

http://www.avast.com/free-mobile-security#tab4

http://www.netqin.com/en/?from=mobile