Bsnl modem idle time data loss

i use a software called sarath cholayils night downloader for rebooting modem at 2am and a software to turn on computer at 1.55am,but bsnl usage record shows that for 10pm-1.56am i downloaded 51mb. How is this possible ,at that time my computer was in sleep mode.PLEASE HELP ME TO SOLVE THIS PROBLEM.

Your system may be infected. Install a good firewall and check the usage at Idle time. You can use Imran's Broadband Helper utility which disable the NIC card till 2.00 am.