iPad 2 crashes at usage I'm using an iPad 2 with 32 GB and SIM-Card-Slot. The sim-card-slot is not in use, so it's empty.
Installed is the latest iOS version (no updates available). I don't use any jailbreak (and didn't used it before). All my apps are installed out of the App Store, so it isn't a development device. There is no "pseudo-background-app" like a anti-virus-scan tool or something like this. The free space is round about 2,5 GB.

Since some weeks ago the iPad is crashing at several usages. I hear music streaming, after some songs it crashes. I write an eMail it crashes after x minutes. I use an app and it crashes after y minutes. The time is always different - sometimes it runs for 2 hours - sometimes it crashes after 2 minutes. If I hear music it crashes in "standby" / "background".

It does not depend on the energy. The effect is the same if it's loading at this moment or it has 100% or 15%.

A crash starts by a freeze. Nothing works, after 1-2 minutes the freeze changes to black background and an dark-grey apple. Then the apple changes to the "standard"-colored (brighter) apple. After some minutes the iPad has restarted. But this is no guarantee that it runs now without a new crash.

Hope anyone has an idea to solve this problem.
Have you tried restoring it? There could be something app or service running that you are not aware of, thats causing it.

I would try doing that.

Restore to new, and install a couple of app and test it for a day or two to see if it still crashes.

Before you do, take a full backup to your computer!

If that doesn't work, you probably need to have it looked at by a pro.