Error(-48) is somekind of hardware communication error. The easiest way to fix it will be to flash the firmware. Here's how to do it.. It will take a while(around half an hour) but its worth it and will also improve the sound clarity of your phone.
What u need :
1) Motorola Driver
2) RSD Lite or Flash&Backup 3
3) Monster Pack(Flash update for(Lseries including SLVR)
Firstly you need to backup all your files that stored on phone memory
because it will delete everything in your phone when you flashing.
Start RSD Lite and let it connect to your phone. If your phone is
not detected (and you are certain you have everything installed),
disconnect the data cable, then shut your phone off, and manually put
it into bootloader mode. You do this by pressing and holding down the
"*" and "#" keys while pressing and holding down the on button until
you see text display on your screen. Now connect the phone back to the
data cable. Now click the button labeled "...".
This will bring up the open file dialog box. Find the file you want to
use (in this case select your monster pack file) and then click the
button labeled "Open".
Click the "Start" button. Now you should see various messages
displayed on the screen as the program processes each code group and
does various other things.
This is what the phone will display during a flash:
After it's finished and your phone has given you a confirmation
tone, you can click "Close" and disconnect your phone from the cable
and check out your changes.
If you should get a message like this where the program seems to hang:
panic. Just close the program, chance are your phone is just fine.
Sometimes this happens. This is usually caused by a checksum error.
There could be more serious cases where you phone appears dead. In this
case try to reflash your file again. You could also try reflashing