Digital photos stored on external drive have gray bars

I suggest you check the power supply of your external hard drive. If the drive is not sufficiently powered it could generate such error. Typically USB powered devices must have a minimum 5 volts power supply to it, suggestion is using a double USB cable (two connections on the PC side to ensure sufficient power) or if your are using a power adaptor then check to ensure the adaptor is not faulty.

Alternatively replace the drive external box with a newer one or install the hard drive directly to the PC.

Hope this help