try to start the database from the server manager as follows :
* be sure to start the listener
* initiate the service ( if working on NT/2000 )
* start the server manager
* connect internal and start up
* if there is something wrong it will give back an error number thus will make it easy to trace the error
I am assuming that you have a problem because the partition is filled , you may extend the partition if you are using windows 2000 in dynamic mode
Hisham Nagia
IT Manager For Development
Oracle Consultant - OCP