Maybe this will help you thanks, to My Samsung Galaxy 3 (GT-i5801) is not being detected by my PC -- What should I do?:

1. Unplug the USB cable
2. On the cell phone, dial the following number: *#7284# Once the last

   is hit, the PhoneUtil application is launched. Choose USB -> Modem and then USB -> PDA mode. The good mode should be PDA. Even if the

   mode is PDA, switch to Modem and then back to PDA.
3. Plug the USB cable.

Maybe this will help you thanks, to My Samsung Galaxy 3 (GT-i5801) is not being detected by my PC -- What should I do?:

1. Unplug the USB cable
2. On the cell phone, dial the following number: *#7284# Once the last

   is hit, the PhoneUtil application is launched. Choose USB -> Modem and then USB -> PDA mode. The good mode should be PDA. Even if the

   mode is PDA, switch to Modem and then back to PDA.
3. Plug the USB cable.