Why does it crash? Mac Minis are some of the most reliable machines on the market, in my experience. Maybe a faulty unit?
Edit: Here's the first line of the crash log (which I'm sending to Apple every time):
panic(cpu 3 caller 0xfffffe0023be8be0): [data.kalloc.16]:
element modified after free (off:0, val:0x0000000000000030, sz:16, ptr:0xfffffe2fffc9bb00)
Looks like a use after free bug.