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91% of drive space on Windows 10 computer used by <Unknown>

The user's Windows 10 computer has run out of free space, and WinDirStat reports 91% of the drive space is taken up by <Unknown>
MalwareBytes ran last night, scanned 455,380 files, with no threats found.  This scan took 4 hours and 10 minutes
I installed the latest MalwareBytes update this AM, and I assume that I have another 3 hours for that to finish.

The only major change that the user recalls is that a Cloud 9 connection to what appears to be a virtual desktop was installed around the time they noticed the computer slowing down.

How should I proceed?   Thanks.

91percent of drive used up by unknown
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Distinguished Expert 2019

Run windirstat as administrator using right click ->"run as administrator", then retry.


That helped greatly!!!!

They are all in the TEMP subdirectory of Windows

Since they are logs, I believe that I can safely delete them, and then find the problem in the program that was referenced.

There are so many event logs:

I opened one of them, and I see info messages, and Error Messages about Quickbooks Pro
Distinguished Expert 2019


You may delete those. It's funny that a program chooses c:\windows\temp and doesn't clean up after itself.

Brian BEE Topic Advisor, Independant Technology Professional


What's even stranger is quickbooks would be writing event log items to the temp directory rather than the event log. You might want to check into that as well if it keeps happening, but if you want help with that I'd recommend a separate question.