How much RAM do you have?
Which OS (presumably XP, but Home/Pro and SP?)?
Is the problem still there with Norton removed? If you need more time to confirm this but still need to go online with the PC, why not use a free anti-virus like AVG and free anti-malware such as Spyware Terminator/Spybot S&D/Ad-Aware SE.
Your HDD temperature looks a little high to me, my Western Digital runs at around 32 °C.