My GOD! all 8 linux machines failed

Most of the result IDs you posted (first column I guessed) are from the same machine (#560899). Can you post the machine IDs?

We'll look into it, but at first glance all the stack dumps look like there's something going wrong in the graphics thread (it lists einstein_S5R2_4.35_i686-pc-linux-gnu.so which is the graphics library). Anything changed at the time when these happened regarding the graphics (screensaver jumped in, logged out, lost connection to the X-server etc.)?

BM