I'm having an issue with a client's computer. The computer is an relatively new HP Envy with an Intel Core i7-4770, 12GB of RAM, and a 2TB hard-drive (Seagate ST2000DM001-1CH164). During his regular use the computer will freeze/hang for about 10 seconds every few minutes. He often has AutoCAD LT 2014 and Quickbooks 2013 Pro open, and sometimes Outlook 2013 as well. However when I used the computer it didn't freeze a single time, even when I had Quickbooks or AutoCAD open - until I was about to leave, at which point I experienced the issue first hand when opening the Windows Calculator. The only difference was that he had the programs open and and was actively using them while I only had them open for troubleshooting and was not actively using these programs. I can not find events in the Event Viewer that correspond to the exact times where the computer hangs. I have already checked to make sure the computer is not using a hybrid / SSHD hard-drive as I have heard that sometimes this could cause this issue with freezing or hanging as well.
More Information:
Quickbooks Pro 2013 Release R12P+U
Autodesk AutoCAD LT 2014 SP1

What I have done so far:
check computer for infections with MBAM and Avast
-removed expired version of Norton Internet Security to prevent issues with Avast.
-updated Avast to latest version
-install latest Windows Updates-Installed the lastest service pack for AutoCAD LT 2014.-Ran checkdisk (with no flags) and it did not detect any issues.
-SFC found some issues but was not able to repair all of them. Did this 3 times.
-Ran offline SFC from Windows 8 boot DVD and still get error message saying it was not able to fix/replace all corrupt files
-Ran Windows Memory Diagnostics which did not find any issues-completely uninstalled Avast to see if Avast was interfering.

Link to windows application logs: https://dl.dropboxusercontent.com/u/...on%20logs.evtx
Link to windows system logs: https://dl.dropboxusercontent.com/u/...em%20logs.evtx

Any ideas or suggestions? Does this sound like a hardware or software issue?