My current kernel line is this:
options "ro root=LABEL=arch arch noapic irqpoll acpi=force noefi"
I'm using nouveau but it also happens using fbdev. I can't get nvidia to work, it just blacks out the screen when starting X.
Any hints are welcome
EDIT: It just happened again, this time just after I clicked on a tab in firefox. I hit refresh, so the spinning circle came up on the tab, and the windows partially reloaded, then the mouse pointer stopped responding. The loading circle then stayed spinning indefinitely with the page failing to load any further.
Further information:
I removed noapic, irqpoll, arch (is that even a valid kernel option?) and noefi from the kernel line for this boot so that all that was left was acpi=force and it still booted happily. I'm not sure if I need any of those, I can't remember why I added them, probably to fix this keyboard issue. I'm booting through rEFInd so maybe I shouldn't have that noefi entry anyway.