Hmmm somthing is seirously wrong with your computer as it takes 16mins to boot up! must have lots of background proceses going off/ malware!!!
Reading you had norton on it. Need to use their removal tool to get rid of norton.
Use crap cleaner to remove all junk files and registry cleaner within it.
download & run malware bytes free to test for spyware and remove what it finds on full scan.
Remove avast free then CLICK MY COMPUTER RIGHT CLICK C: DRIVE OR ROOT DRIVE WITH OPERATING SYSTEM / PROPERTIES /TOOLS /ERROR CHECKING Tick check now/repair and recovery bad sectors & reboot. After that run defrag in run box
after that repair job if your sound works download sp3 through windows update and go to that and reload avast.
It should be quite quick with 256mb of ram installed but is bare minimum for reliability 512mb on my computer is plenty like a rocket!