did you have a cloud of steam outa the exhaust, there is a chance the head or block is cracked or warped, could even be dumping into the oil, if you changed the head gasket i guess u no what ure doing but just incase and if anyone else needs to no the things to check....

1. oil in water in the header tank, will be on the surface so easy to see
2. water in the oil, will be a mayonaze looking substance on the oil filler caps under side.
3. water in oil again, realy high level of oil in the engine on dipstick, probly be a grey color
4. water dumping into piston, big clouds of steam
5.oil into piston, black smoke from exhaust.

if any of these syptoms fit the bill let me no which and we can go into what the possible causes are.

if none of these there is allways that u didnt put in enough water!!! did you run the car in the drive and top up after a few mins??? normaly takes a while to get all the air out!