There's a folder in the root of my C drive with a 30-character-long, hexadecimal name. I've asked my colleagues about it, but none of them have this folder.

Inside the folder are a few files:

  • install.exe
  • install.res.dll
  • microsoft_defaults.exe
  • silverlight.7z
  • silverlight.msi
  • Silverlight.msp

I've run a malware scan on them, no issues detected.

What are these files for, and are they safe to delete?

  • Probably a temp folder. That's why its name is soooooo long. I think it's safe to delete. – Chen Stats Yu Feb 21 '16 at 22:03

Let me guess: its name is comprised of numbers and lowercase letters from a to f, something like 855fbe9f71206fdd447d256e235b.

These folders are harmless, though perhaps a bit of an eyesore. They're supposed to be temporary storage for programs' installation data, and thus are generally deleted automatically once the installation is complete. However, they're sometimes used to store the uninstallation media as well, in which case removing them would make it impossible to uninstall the program via normal means. Fortunately, Silverlight is well-behaved in that regard - if the files aren't in use (i.e. if there's no update installation going on), you can delete them.


No, I don't know what the files are for, and I think chances are quite good that other people will also not recognize this particular collection of files. They do look safe to delete.

Silverlight is not commonly distributed, as an official installer, as a silverlight.7z file. So it appears this is something custom.

The silverlight.msi is a Microsoft Installer file. You might find that some or all of the 5 other files might be located inside the silverlight.7z file. "install.exe" sounds like a very generic name, so if it is something different than Silverlight, the filename is not a detail that is sufficient enough to identify what the file is. (In Explorer, you may be able to Right Click on the file, choose Properties, and see some information, like the name of an organization that helped to create the file.)

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