Background Information / Computer Specs

I have a 14-inch Samsung Series 5 Ultra. Core i5 CPU, 750GB HDD, 8GB RAM, Intel HD Graphics 4000. I've had the computer for about 1.5 years with no major problems.

Problem

The issue appeared at the beginning of April this year, when I updated the OS to Windows 8.1 Update 1 (not from 8 to 8.1). After being on continually (except for at night, when I put it on sleep mode) for about 48 hours, the disk usage as seen by Task Manager hits 100%. When this happens, everything from opening/closing applications to typing and even bringing up the start screen by pressing the Windows key becomes extremely slow. The only way to make the disk usage decrease is to restart the computer. Then the problem repeats. I've used my current laptop (as well as my previous laptops) this way -- putting it on sleep mode at night and restarting it only when Windows needs to install updates -- for a long time. So I know the 100% disk usage is not due to the way I use the computer.

The thing that causes the spike varies. Sometimes it's System, sometimes it's one of the various applications I installed (e.g. Chrome, Evernote, Spotify, Wunderlist, iTunes, etc.), and sometimes it's Antimalware Service Executable, etc.

Tried Solutions

I think I tried almost every solution out there for this problem:

• Running the check disk command (chkdsk /b /f /v /scan c:) from Admin Command Prompt
• Running Windows Memory Diagnostic
• Disabling Superfetch and Windows Search from services.msc
• Running "Fix problems with Windows Update" from Control Panel --> Troubleshooting
• Updating and rolling back the graphics driver (Intel HD 4000)
• Disabling "Use hardware acceleration when available" from Chrome settings
• Disabling Intel Rapid Storage Technology
• Running the SFC /SCANNOW command as recommended here
• Running a quick scan & a full scan from Windows Defender (no threats found)
• Taking the hard drive out and putting it back
• Refreshing the computer, from the Update and recovery --> Recovery option in Windows settings

NONE of the above worked for me. I was about to give up but then noticed that one of the main culprits of the disk usage spike, as shown in the "Disk Activity" section of the Resource Monitor, was C:\System (pagefile.sys). I googled around and found that one of the recommended solutions was to disable pagefile. I then went to **Control Panel --> System and Security --> System --> Advanced system settings --> Advanced tab --> Performance settings --> Advanced tab --> "Change" under Virtual memory and discovered that the number for "Currently allocated" at the bottom was 1280MB, although the number for "Recommended" was 4533MB. I immediately changed it to 4533MB and checked my family members' computers to see what the numbers were like. All of theirs had a currently allocated space that was only slightly smaller than the recommended space. See screenshot below:

This might fix the problem. I'll have to wait a couple more days.But if it doesn't, what in the world should I do next? I'm guessing the hard drive isn't failing because

1. This computer is less than 2 years old; and
2. Speccy says that the status of the HDD is good.

Update 5/27/2014

The "4533MB" solution did not work. I had to reboot the computer about 30 minutes ago because the disk usage again hit 100%. When I opened Resource Monitor the C:\System (pagefile.sys) again was shown to be the culprit. I have now disabled pagefile entirely via the same window shown above in the screenshot. The number for "currently allocated" is now 0MB. Will update again in a couple days, or if the problem occurs again, whichever comes sooner.