need to add something somewhere about usb chipset issues (bug report: http://markmail.org/message/smxnofrdmmkxyvnd)
one affected chip is http://ark.intel.com/products/32432
solution during boot is to escape to loader prompt, type:
set the hint to install and once again in the loader to boot the install, then add it to loader.conf
the issue is with the acer product specifically the bios settings for the HPET timer in the 2920z model laptop
not specific to the merom2 chipset
so, would probably be more useful in a HCL section if you have one
put an entry for like acer 2920z laptop, (requires: hint.....