I have a Samsung Captivate and have tried to connect to my PC to transfer photos and music from my PC and to share photos from my phone. Connect by usb cable but get a message that the connection is to an "unknown device" or "device not working properly". Does anyone have the answer? This is my first Android phone but never had a problem with earlier phones.
Captivate USB can operate in couple different modes: Kies (for firmware update), MTP (for media sync) and Mass Storage.
For Kies, you need download and install Kies Mini so that you can update official firmware.
For MTP, there is no driver needed unless you are running old OS like XP. Drivers can be downloaded from Samsung support page.
Mass storage is a little bit involved. You connet USB first and selected Mass storage mode. Then you need to hit the button to mount the USB storage before your PC can read and write to it. No drivers needed. Maybe XP need Mass Storage driver which is the same driver you download from Samsung.
To check or set which USB mode you want your phone to be, Open Settings app (or from home screen, menu->settings) and go to USB, select the mode you desire or you can select prompt to chose mode every time you connect.