Could you please update us with the below information ?
What is the operating system installed ? (Win XP/Vista/7)
What service Pack ?
Do you have/ previously had any other security software installed ?
What is the RAM size of the PC ?
How old is the computer ?
Also, try running MVT from here http://mvt.mcafee.com and update us with your session id .
I am runnung XP SP3
Malwarebytes Anti -Malware
3.0 gb RAM
it is about 3-4 years old.
I could not run MVT because I had to remove McAfee to make the computer usable. After I remove McAfee it has been working like new