My dell dimension 4600 pc has got a problem.  Whenever it starts up it comes up with a blue screen saying that there is an unmountable boot volume and therefore windows cannot be started.  The computer will also not run in safe mode or on last known good.

This problem occured after the computer went into standby mode after turnin it on and coppying a word file onto a CDRW.  none of which to my knowlege could have caused the removal of a system file.

Is there any way i could get my computer to work again (preffebly by monday 12:15 - it is kind of urgent)