|The fact you don't get an error message after a few minutes--much less 5 hours--likely means it's froze up and not hanging with some hardware problem.|
Open it up and clean out the dust. Make sure the cpu heatsink and fan assembly is correctly installed, spinning and free of dust.
If that doesn't change anything go ahead and remove all the cards except video and disconnect all the drives. (Make notes about their positions for reinstall, if necessary.) Then start it up and see if you get past that particular stage of the posting process.
Real men don't use AntiVirus; they just reformat