I have not - how do I do that?
http://windows.microsoft.com/en-us/windows/create-shortcut-map-network-drive#1TC=windows-7I'm not on my Win 8.1 machine so I cannot confirm if it's the same protocol.
Why would you want to do this? (rhetorical): I've found in the past that Windows networking will reestablish the network path faster if the drive is mapped, plus it will give you nice warnings about whether or not the NAS is accessible on bootup.
After mapping the drive, you'll need to point your MC library to it. First, make a library backup. Next, select all of your media, right-click, and go to Rename, Move, and Copy Files under Library Tools.
In there you will want to select 'update database to point to new location'. Under find and replace, replace your windows share paths (ex. \\YOUR-NAS\Media) with the new locally mapped drive letter (ex. Z:\). Make sure everything looks good in the preview window and click OK.
If this doesn't rectify the problem, you might want to mess with your NAS power settings such as the hard drive spin down interval.