Time For A New Motherboard?

I use Clonezilla Live to back up a PC drive to a portable external HD
with a USB-A cable.

Recently Clonezilla Live has not been able to complete the job...
It basically seems to hang anywhere during the backup process. The
time left to complete the backup shown on the screen increases
continuously and the % of backup already done does not change.

I know that there is nothing wrong with the Clonezilla Live DVD or the
portable external hard drive because I can back up another PC's drive
without a hitch using the same USB-A cable.

My guess is that I have a USB port problem with PC#1 and it might be
time to purchase another motherboard. (The PC is nine years old...)

PS: I have tried using all the USB ports that are present on the PC
with the same results.

What do the experts think of this issue?

--
tb