This happens to me to but only sometimes.

I also have the same problem.

The MediaMonkey app closes after a few seconds of playing.

The library did finally finish scanning but app exits before first song finishes playing.

If it helps, here is the event viewer log after installing the most recent version of the media monkey app:
Faulting application name: MediaMonkey.exe, version: 0.0.0.0, time stamp: 0x511563d7
Faulting module name: ntdll.dll, version: 6.2.9200.16420, time stamp: 0x505aaa82
Exception code: 0xc0000374
Fault offset: 0x000da94f
Faulting process id: 0x2c40
Faulting application start time: 0x01ce0991978b6263
Faulting application path: C:\Program Files\WindowsApps\F9C317A9.MediaMonkey_1.0.1.27_x86__6npfwtawc6s18\MediaMonkey.exe
Faulting module path: C:\Windows\SYSTEM32\ntdll.dll
Report Id: eb8c0153-7584-11e2-be7c-00012e2cacbc
Faulting package full name: F9C317A9.MediaMonkey_1.0.1.27_x86__6npfwtawc6s18
Faulting package-relative application ID: App

I was anxiously awaiting the release of this app and many aspects look promising. Unfortunately, I have been unable to get the app to work properly. I have tried on several computers and am having the same issue on both. Both computers are running Window 8 64 bit Pro and are attempting to read FLAC music stored on a Windows Home Server 2011 share (library is ~12,000+ tracks).

Here are the steps for recreating the issue:
1. I have a library for FLAC music on the Windows 8 machine
2. I install the MediaMonkey App
3. I go in to Setting -> Scan for media
4. Remove existing folders and add the FLAC Music library.
5. Wait while it starts adding files.

At this point if I click to play a file it plays for ~5-30 seconds and then exits out to the Start screen. I also tried letting the scan run overnight but the scan fails to complete (some tracks are not added). Whenever I open the app at this point it seems to attempt to scan for files (I don’t think it has ever completed successfully). If I attempt to play any files the file starts to play but then the app closes within 5-30 seconds.

I am not sure if this is a known issue. I see that the app is using a large amount of memory and others have reported that issue but I am not sure if this is related or not.