Please help me!!!! I dont know what to do? This is very important your my last chance?

I dont know what is going on? All of a sudden my computer doesnt work right. It is going extremely slow. I used to be able to log in in a matter of seconds but know if Im lucky Ill get on within 10-15 minutes. And to get online takes forever, I have cable/dsl and it waas so fast but now its so slow all of a sudden, I dont know why. Do you? It seems like everytime I go on it gets slower and slower. I cant take it anymore. I have been doing scans with norton antivirus which is what i have and its been goin for this whole day and still it found nothiung wrong with the computer. How can this be if it is going so slow. Something that has been popping up is the computer saying its too low on virtual memory and its currently making more but thats been coming up since forever. And all of a sudden i keep getting this pop ups from internet explorer for avssystemcare or something like that. I tried downloading it but it said it wasnt able to. I know i downloaded this thing called

Please help me!!!! I dont know what to do? This is very important your my last chance?microsoft

Press Ctrl+ALt+del sort memory usage in descending order...lok for the process tht is unusual nt listed by any of the known programs installed on the pc.If found click nd end the process.U hv a spyware problem.The best free utility i hv ever used is Spybot.U can grab it frm the below link.