could I have a virus on the pc?

[556]

Earlier I watched a video a link comes up but stopped the video didnt do anything then I went down stairs come back up stairs pc reset itself don't know why I reset it loads of times wouldn't let me do anything Double click on.google chrome my computer it just loads but doesn't do anything its so slow did system restore on safe mode deleted temp files chkdsk it was still slow and as I cant do.chkdsk on desktop managed to do task manager couldn't find anything tho. I have xp and i'm . wondering if I have a virus since its not loading what I click on plus I cleaned pc out for dust so thinking I have a virus how do I get rid of it? Was gonna do a reinstall but disk kept saying ntldr not found so couldn't do the reinstall.
I have avg on my pc