Msocache is another of those “magical” directories (not a file) that somehow just appears one day. Since we’re not looking for this kind of thing constantly it’s easy to miss exactly when it showed up.
Here’s one clue, though – MSO stands for MicroSoft Office.
Yep. Microsoft Office is trying to be helpful.
First, Microsoft does have a Knowledgebase article on this, though thetitle’s not particularly helpful: LocalInstall Source (Msocache).
The bottom line is that it’s simple a local copy of Microsoft Office’sinstallation source. Put another way, it’s a copy of portions of the MicrosoftOffice installation CD. Why? so that you don’t have to insert the CD when youadd a feature, perform a repair operation, or install service packs andpatches.
Msocache is created, quoting the KB article:
…if the following conditions are true:
One of the available hard drives has more than 1.5 gigabytes (GB) of freedisk space available.The hard disk with sufficient space is not a removable drive or a networkdrive.
Personally that seems kind of arbitrary, but there ya go.
You can delete the folder, but, that same Knowledgebasearticle goes on to say, “Never delete the MSOCACHE folder by using MicrosoftWindows Explorer.” Why, I do not know. They suggest using the Windows DiskCleanup Wizard.