I have a hidden file called MSO Cache on my E drive. Windows XP is installed on the C drive. Msocache is about 200 megabytes but it looks kind of important. I'm sure I didn't make it nor anybody else. Is it a system file or spyware? What does it do and can I delete it safely? 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 the title's not particularly helpful: Local Install Source (Msocache). The bottom line is that it's simple a local copy of Microsoft Office's installation source. Put another way, it's a copy of portions of the Microsoft Office installation CD. Why? so that you don't have to insert the CD when you add a feature, perform a repair operation, or install service packs and patches. Msocache is created, quoting the KB article:
Personally that seems kind of arbitrary, but there ya go. You can delete the folder, but, that same Knowledgebase article goes on to say, "Never delete the MSOCACHE folder by using Microsoft Windows Explorer." Why, I do not know. They suggest using the Windows Disk Cleanup Wizard. Related:
Article 9428 | Posted November 17, 2005 |
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" 'Never delete the MSOCACHE folder by using Microsoft Windows Explorer.' Why, I do not know."
Because you will hurt MicroSoft Office's feelings.
Posted by: Bubba at November 18, 2005 2:04 PMI have used diskcleanup to get rid of MSOCache but it still remains. The dirs are actually on my H: drive. My other problem is all my attempts to update MS Office 2003 fail.
Posted by: Bill at December 20, 2005 4:20 PMI can't even get windows diskcleanup to get rid of it as it wont recognise its existance. Bets left alone, dont want to upset it ;)
Posted by: Tod at May 13, 2006 10:37 AMTod
www.linkup-media.com
Here is a partial solution. Uninstall Office 2003. Reinstall it. On the Setup Completed page, check the box next to Delete installation files. Click Finish. Install Office 2003 Service Packs 1 and 2 and all the Office 2003 updates from the Microsoft Update site. Clean your Windowss Registry (with a program like Macecraft's jv16 PowerTools 2006 Registry Cleaner). Run Disk Cleanup. It will find all the files in your MSOCache folder and delete them, but will not remove the folder itself. Must be Microsoft's Revenge ...
Posted by: Avner Falk at June 17, 2006 2:56 PMP.S. After all the above, manually delete your MSOCache folder in your Windows Explorer (despite Microsoft's warning), then rerun your Registry Cleaner, which will find a few dozen new invalid entries in your Windows Registry. Delete those, and your problem is solved (hopefully ...)
Posted by: Avner Falk at June 17, 2006 3:02 PMI use a little program called unlocker that is a freeware I got off the internet and deleted it with no problem!
Posted by: painterr at September 1, 2006 2:58 PMThe reason you should not just delete this file with windoze exploder is that it has registry entries pointing at it that will remain behind after the delete, and will bite you later.
Posted by: Mark Plant at May 21, 2007 4:48 AMYou can use this tool (see direct-to-download URL below) from Microsoft to cut back on what is in the MSOCache directory, or to remove all Local Install files period. Very handy - why it needs to be done with this (or assumably a DOS prompt when Windows wasn't booted (ie: A boot disk or recovery/repair console) I don't know... But this IS the "official" way to "uninstall" the MSOCache files.
http://download.microsoft.com/download/b/7/b/b7b7d0e1-f125-46ed-9d65-95350e8d3f96/LISTool.exe
Posted by: WeyrleaderZor at September 24, 2007 12:04 PMthe uninstall tool does not work for office2007 there is no mso.dll
Posted by: none at December 28, 2007 10:14 AMWhy keep the files if you have them? Windows update may/will fail with Office updates, probably other tools as well, if you delete the files without cleaning up the registry. I'm currently in that situtation. Even changing drive letters can affect if the auto-update finds the installation as being not intact; move your CD/DVD to drive Z:. It tries to open files where it thinks they should be and may conclude that the installation is corrupted and stop. In my case, I removed the default Acer laptop D: partition, single drive with two partitions, after I installed Office. Windows update will no longer auto-update Office. It fails for all updates. No going back in my case. Now I'm trying to find the correct registry entires to remove or blank contents to avoid this check from failing the update.
Posted by: Matt at September 29, 2008 1:02 PM