I don't think so. If the attacker got physical access to the hardware there is very little you can do via software, given the architecture of normal computers.

I don't think so. If the attacker got physical access to the hardware there is very little you can do via software, given the architecture of normal computers. So the only thing that makes sense is to find a way to detect physical access, and currently the only one is to physically protect the computer itself. Edit: still there are a few tricks that can be done in theory. For instance to flash a new bios modified in order to write some data in a given sector of the disk if after the power up you don't press a special sequence of keys. This makes the owner able to detect if there was access to the PC, and because it's done in the BIOS even starting a different operating system from the CD will not avoid the detection. This is security by obscurity, but can work against Maids. Another simpler, less effective, but still better than nothing approach is to set a password in the BIOS. Unfortunately if I remember correctly a lot of BIOSes used to have backdoors.