Hacked

Recently on Ebay,I hired a webmaster to build my proposed site(never again,not in person).
Their conditions where,half now,balance when happy.
A third of the way through they wanted the balance ,when i wouldnt submit they ceased everything.
I got my deposit back through paypal,them my computer began shutting down at odd times:confused
Although I unplugged my modem for 12 hours at a time to change my IP address.
My question could this person be responsible for my computer shutting down(I have since got a new one?

 

Change your passwords, get a firewall, disable remote accesss to your computer.

http://answers.yahoo.com/question/index?qid=20080314072055AAsbkcR