in that case you would be leaving your lappy toppy behind...
BAA etc want to see if the lap top works because the circuitry can hide explosives inside fromt the xray. By seeing the computer will power up you are easing the load on the xray reader so more bags can more through more quickly.
File scanning however will show nothing apart from will it work. A better suggestion would be to check the DVD player works or all the ports. File scanning isn't going to prove anything BUT the security guards don't know and so they think they are being clever... as if looking around a filing system is the same as looking inside the physical case... I mean, really LOL....
Anyway, refusal of course will mean they'll not let you through which means you'll miss your flight. Which isn't really why folk go to airports. Worse, under UK legislation at least, refusal probably means that you are giving reasonable cause which means they may just take a screwdriver to the mother board in a back room where they keep the dogs.... Perhaps a worthwhile strategy for a new laptop on insurance then!