What's your theory on why your screen instances are dying and how would EC2 be responsible for it?
The contents of /var/run/screen/ and the "S-<username>" subdir that should be there...
The output of "ps u" and "ps -ef | grep s[c]reen"
Sounds like you're got a configuration problem somewhere (os on you instances, software you're running, etc.) on your end and are blaming amazon for it when they had nothing to do with it.
Now, potentially the instance is on bad hardware (start/stop if you've got no ephemeral storage which will put you on new hardware) but that can happen even if you're running your own hardware. However, you've done so little investigation that blaming amazon is downright bad IT (is this how you deal with other bugs, blame the first thing you can think off and rant about it?).
I am at work. I log into an EC2 instance via ssh. I establish a screen session. I do some work inside of screen. Go home after work, leaving screen running.
I arrive at work the next day. Log into EC2. I type "screen -ls" and I am told that there are no screen sockets. (In my experience, this usually means the server has been restarted.) I am annoyed. I create a new screen session and proceed to get some work done. That evening, I leave the screen session running, and head home.
I arrive the next day at work. I log into the server. I type "screen -ls". I am again told that there are no screen sockets. I am now very annoyed. I start a new screen session and proceed to get some work done. That evening, as before, I leave the screen session running, and I head home.
I arrive the next day at work. Once again, I log into the EC2 instance via ssh. Once again I type "screen -ls". Once again I am told that there are no screen sessions.
This happened 4 days in a row.
I was left feeling angry and I was left feeling like no EC2 instance could be trusted. I also feel like it damages my productivity that I can not rely on screen (I have in the past, on regular Linux servers, had screen sessions that lasted for many months).
Right now I have all of my personal sites on the Rackspace cloud, which I think was taken over from Slicehost. Although this is called a "cloud" service, the "slices" feel like real computers to me -- I can have a screen session that lasts for months.
The EC2 instances are strangely insubstantial, even when compared to other services that promote themselves as cloud services. Personally, I prefer to work with services that are at least solid enough that I can rely on screen sessions.