my pc was at data copy speed of 30 MBps and now only 700 KBps i think there is a virus in my pc i already tried in 2 pcs and difrant mmc cards and flash drives. and also try this mathod.
1.Right click on the USB drive and select properties
2.Select the Hardware tab
3.Under All Disk Drives, highlight your USB drive and select Properties
4.Select the Policies tab and select Optimize for performance.
5.Press OK
But nothing happend please any expert