Both the cord and pc worked fine on my Incredible, before and after trying on the Ally. Tried all the USB ports as well.
With the Incredible there is a "connect to pc" option under settings, is there no such deal with the Ally? I looked everywhere in Settings and could not find anything.
From the home screen, once connected, make sure there is a usb icon in the notifications area. Then, pull down the notification taskbar and tap the "usb connected" message. You should then be good to go.
Try going into "settings-->applications-->development-->USB debugging". Enable this. This may give the Ally the kick needed to enable file transfer between device and PC.
It is tough to diagnose and try to fix. He will not try at home...says he doesn't have the time. We have tried at work where my Incredible connects just fine. But downloading the USB driver file at work is not going to happen.