All Data not inserted in website from excel

Hi.I have 1000 records in excel .it work fine for 1 to 150 almost after this not able to save to website …
Although the loop is working fine from 1-1000 Records.
To verify the procedure ,I have restarted the Application again and then i found it inserted next few almost near about 120 to 150 records fine to the website .

to verify the inserted records ,I have created a Extra column named as Flag and it gets set to true ,once the record is inserted into website .

This whole process is taking about 8-20 hours time due to complexity and what i observed is that this Issue only occurs when this application is executing in back end and my windows are locked .Where as when i unlock my system then again it works as expected and start inserting the records .
This is mainly due to my locked system.
I already done simulate type true.
@Palaniyappan @Pradeep_Shiv