ORA-09968 :: Unable To Lock File?

I am using Oracle 11g in my Windows machine. I wrote a multithreaded program that will be inserting into Oracle database so I was getting this exception before-

ORA-12519: TNS:no appropriate service handler found

So after going through various article on the internet. I found that the solution for above exception is to increase the number of processes- So I followed the below thing and it works fine for me after that.

cmd>sqlplus / as sysdba
sqlplus>alter system set processes=300 scope=spfile;
sqlplus>shut immediate;
sqlplus>startup

Now after some more time, I increased the processes to something like below

alter system set processes=1000000 scope=spfile;

And since then whenever I am starting up my Oracle database, it is giving me this exception below and it is happening since one day.

ORA-10997: another startup/shutdown operation of this instance inprogress
ORA-09968: unable to lock file