"I hooked up the drive to another computer (XP) and... it did burn, though slowly (could be the computer too: it is very slow and it was downloading winodws updates at the same time)."
Apparently the minimum recommended for the SE-S204N is CPU Pentium 2.8ghz or above, so if the computer is slower than that or if it's slower for other reasons, the burning would be slower.
Samsung (TSSTCORP) SE-S204N Manual
So it appears there's .nothing wrong with the external optical drive itself.
Your problem is probably directly related to you adding the USB hub.
External hard drives and external optical drives require that the USB connection has to be able to supply the full 500ma the USB specs specify.
In Device Manager - USB controllers, the Power info for the Root Hub the external drive is connected to probably says Power required 500ma for this external drive - Windows probably gets that from an *.inf file or similar and that isn't necessarily what the drive is drawing at that moment or can draw.
Burner drives draw the max power from the USB connection while burning, a lot less when just reading a disk.
If the computer you had the external drive connected to when you got those errors is a laptop computer, some laptops cannot support USB devices drawing 500ma per built into the laptop USB port when there is more than one device plugged to the built in USB ports. If only one device that requires 500ma is plugged into the built in USB ports that device works fine, but when you also plug in other USB devices into the built in USB ports, at least one of the devices plugged in will NOT work fine if one device requires 500ma.
If you connect only the external drive to the built in USB ports, it will probably burn disks fine.
If the computer you had the external drive connected to when you got those errors is a desktop computer
- the external drive should be plugged into a USB port directly connected to the mboard
- the wiring between a case USB port and a USB header on the mboard, or between a port in a plate in a slot space on the back of the computer and a USB header on the mboard, may not be adequate to support drawing 500ma from it or it may be unable to support a USB 2.0 connection properly.
- some multiple USB ports on the front of a case may not be each be connected to one USB header connection per port - they may be two or more ports connected asa hub to one USB header connection and be sharing the 500ma available. Usually the two front ports near the bottom of the front of the case DO each have their own USB header connection.Ones higher upon the front of the case often do not
If you have a desktop computer, Note that I answered a Topic on this site where a guy had an external drive, which does require the full 500ma, connected to a port on the back of a desktop case - it would not work properly when a webcam was in the port next to it, but it worked fine when the webcam was unplugged. Ports on the back of a desktop case often have two ports connected to the same USB controller module that are ports one above the other - you could try connecting the cable to one of those and leaving the other un-used.