I'm pretty sure that the freezings and crashes are related to the tags and/or file names. I have 2x64 GB full of FLAC files, and I haven't experienced any crash, not even once. But, my files are very clean, and all have their tags well done.
What I do see, however, is strange symbols in some file names that have accents or not-english letters, such as "ö". Something might be broken there.
I think Fiio should release firmware updates more often, even if it means less bugs fixed on each iteration. There are some bugs that are very easy to fix, and should have been fixed by now.
For all that are experiencing crashes, I would try starting from scratch and adding one album at a time. You may find out that just one album or one song is causing you the problem.
I can confirm 100% that my crashes were due to tags and/or file names.
On the X5 I had a folder with 7 of my best songs. If I left the X5 shuffle these 7 songs it would crash eventually, sometimes after an hour, sometimes after 3.
I redid all the tags properly as well as the file names and my X5 has been running non stop since 1:30AM last night playing those fixed 7 songs. It is now 3:34 PM which is 14 hours, the LONGEST my X5 has ever ran without crashing, on the same songs that used to crash it the most.
The main things I fixed in the tags/file names as follows:
-"track name.(blabla.Music.vol13)" changed this to Track Name.
-All tracks purchased from Beatport follow this format: 576575_Track_Name which I changed to Track Name
-Some of my album art had a large file size like 250kb, removed the originals and replaced with smaller file size arts (from Beatport and soundcloud as they follow 500x500 format)
-Some of my songs had 3 album art images... somehow itunes overlapped multiples? Removed all and replaced with correct album image
Now I only have to do that manually for 1653 more songs. Beatport purchases = no tags
Rumor has it Itunes will start selling lossless music (what with Apple purchasing Beats by Dr. Fart Cannon) which I look forward to.
Thanks to Lee730 for his suggestion to fix my tags =)