what does this message mean?

twice now in the last month i have had this message on starting up from standby (2nd time today) I may have missed some out as i was panicking a bit, not being too computer literate!
'Bugcode-usb-drive
check to make sure any new hardware or software is properly installed.
Disable or remove any newly installed hardware or software (there isn't any). Disable bios memory options such as caching or shadowing. If you need to use safe mode to remove or disable components, restart your computer, press f8 to select advanced startup options and then select safe mode.
Dumping physical memory'
What does all this mean and why is it happening? What is physical memory? I restarted the computer both times and everything seems to work as before. Can anyone please assist?