I have installed oracle 11g on window7 OS.After that i have manually create database using the pfile.When we start database everytime showing error boot strap segment failed in alert log file.Then we start database at startup upgrade command.after that we open the database alter database open command.Then after that we use alter database datafile 'path/system01.dbf' autoextend on command and also use alter database datafile 'path/sysaux.dbf' autoextend on command. At that time database is started.then after sometime again boot strap segment error comes.Pls suggest