Have you just taken delivery of the machine? If so, did you remove the restraining/transit, bolts prior to use? If it's been in position for a while and working fine until now, the only two places that would require anything like a 3" screw, on a washing machine, would be to connect the concrete balance blocks to the drum, (although they tend to be Bolt type heads). The other is the four long screws that hold the motor together.
TURN OFF AND REMOVE PLUG before taking the lid off. Take out two small screws at the back and push the lid slightly back from the front of the machine, this will allow it's removal. If all the concrete holes and screws are visable and tight, tilt the machine onto it's back feet. NOTE: Get someone to hold it whilst you look underneath, (FOR SAFETY). Check the other concrete block, and see if all present and correct there.
ALSO whilst underneath, look at the motor, (the large silver unit near the rear of the machine and has the drive belt for the drum attached.
Look carefully at the either end of the motor, compare the retrieved screw to the type on the motor then see if all screws are in place and tight. If not, replace the screw in the respective hole and tighten, checking the rest also in case of them being loose.
Check these two options first.......
Davy Mac, June 2009