Why is my cpu usage so high?

So my computers cpu usage is is high it ranges between 0 and %30 some times spiking to %100 the computer is a compaq with windows xp I have run a ad-aware scan a virus scan nothing happened when it is in idol the task manager says that the cpu usage is in the 90s it never falls below 93 I currently have 49 nine processes running and as far as I know none of them are viruses or anything like that there are no applications running in the background I do not have many things downloaded to this computer I did download process explorer and it is saying that my DPCs are taking up between like 3 and %23 of my cpu sometimes it takes up to %43 I do not know what DPCs are so I did not end that process I do not know if this matters or not but I have two networks going in the networking page in the task manager one of them is non operational oh the PF usage in the performance tab in the task manager is 590 MB oh and I have noticed that right before the cpu spikes the entire computer freezes but just for like a second oh and videos and music they do the same thing right before the cpu spikes it stops just for like a second so if you can help please do thank you in advance