John L

I also agree that the issue is not related to specs, if Realms servers are experiencing this problem then it should not be a spec related issue. 

This could also be related to servers taking up massive amounts of CPU and memory even with 0 players online, it could be generating lag and issues itself.

Just something to add: I have a mob spawner farm for skeletons near the surface, i have it made out of glass but covered with cobblestone, skeletons are burning during daylight when light sources are bugged in this chunk, perhaps lighting as a whole is broken in certain chunks when bugged.

Edit: The skeletons do not burn during daytime if the chunks have been "Upgraded", only occurs when the chunks bug again

Edit Replication: 

1: Make a mob farm at a skeleton spawner near the surface out of glass tubes

2: Cover glass tubes in cobblestone at the top

3: Enter nether and leave nether back to spawner until light sources are bugged

4: During daytime, the skeletons should burn when reaching the end of the farm, depsite behind shielded by cobblestone

I tested it Katie. It does it to all the minecarts with a block in them. So all except the player riding one.

It's not the same, this is for iOS, not on the computer, it's different.

I put comment on the screen shot but I'm not sure if it went through. Here is the set up,

in the top right is a normal chest (filled with random items)
that's a powered rail in the back
an activator rail above a hopper which is above a trapped chest
hopper minecart

I can't tell if the item is really disappearing OR if it's staying in the cart (as this is single player).

I do know that it's its staying in the cart it's most definantly NOT being put/stored into the hopper above the trapped chest.

Of course, im talking about when I have the trapped chest open.

thats a minecart hopper.
a powered rail, powered to keep it moving
a hopper under that activator rail
a trap chest under that
a regular chest in the top right

I just reproduced it on single player. Java version 1.7 10. Version 1.4.6. NO mods/plugins/allocated/etc.

Rememberme1's crash report for 1/3/12

I just want to say that I reproduced this bug on my test server with 1.4.6. It did corrupt the chunks. But it took way more than 3 jukeboxes. I had to be in creative mode and destroyed like 15 in a row. Oh, none of the juke boxes had CD's in them too btw.

At first It crashed me with 3. But no one else on the chunk. I then realized that my personal java wasn't updated. So, I updated java to 1.7 v10 (both 32 and 64). Then I went back in and destroyed a bunch in a row. This time it corrupted the chunk. No one could get near that chunk or spawn in the chunk.

my server has 8gigs of ram but my processor sucks 2.0 quad. So since it drains the memory, maybe I had to kill a bunch to reproduce compared to others who may have less ram. BTW my server java is 1.7 v10. (we updated because of these forums).

To be fair I know this is a vanilla MC bug. I did reproduce this on MC server with about 7 plugins running. I'm letting you know this because it does make a difference. However, this bug is a big one as it will literally corrupt the chunk.

I guess I can test it on single player too. But I allocate a ton of ram to my MC as well.

Ill get back