i need help!!!

[acdcrock666]

hi, i am not that good with pc's and i need some advice badly can anyone help me please? I had a warning from norton anti-virus after i did a virus scan saying i had one threat that was fixed and it was a trojan threat, i veiwed the scan details and it said it had fixed it and i needed to restart my computer, so i did. When i logged back in it worked fine for about 5 miniutes and then crashed, i could not do anything not even move my mouse. I turned it off again and logged back in and i clicked on norton and it did not work, i then tryed going on the internet useing internet explorer and i was connected to the internet but it would not let me search anything, and now it just keeps crashing everytime i log in to try and do something.... can anyone help me a give me some advice please, thanks......