2002 Volvo S60 Gauges and lights are on the dash

I dont think replacing the headlight has anything to do with your dash going out intermittantly. What happens when the dash comes back on? Is the SRS light on along with the ABS or anti skid light? If it is then you have a problem with the network. If not then most likely your drivers information module is going out. If it is bad you will need to take it into the dealer or a shop capable of downloading new software to the replacement module so it will be better if you have it diagnosed to verify what is going on.