MDS Error: /var/folders/lM I've been getting this error coming up in my system log.  Having looked around for an answer, two things came up commonly: a problem with the spotlight database(s), and permissions on those folders.

Well, I played with permissions and even deleted some of the folders in question to see if they would be re-created properly.  I think that was a mistake, there were odd side effects, so I tried my best to restore the folders to the way they had been previously.

Also, resetting MDS didn't help much.  Most recently the error comes up when Outlook refuses to get my mail properly.

It's also always followed by Quicklook-related errors as well.
From Apple Support Communities, with some correction:


Command-S at startup for Single User Mode
Repair the files ystem as indicated on screen using fsck (took three runs)
Mount the file system as indicated on screen, /sbin/mount -uw /
Go to /Library/Caches and do rm -rf *
Go to my home folder /Users/.../Library/Caches and do rm -rf *
Remove a Spotlight folder, rm -rf /.Spotlight-V100
Go to /var/folders and do rm -rf *
Start normally using exit or reboot command as indicated on screen


Be extremely careful with the rm -rf commands! To double-check that you're in the correct directory: 

pwd


I hope that helps!