PREFACE: Sony's web site states clearly that the DRX-840U is a plug-and-play device that Windows should recognize and because of this, there are no downloadable drivers available for the drive.
I have a Sony DRX-840U external DVD reader/writer. I'm having a problem with DVD disks being put into the driver that take a long time to be "recognized" by the drive. I'm not sure what the correct terminology is here, but with DVD drives some DVDs take a long time for the drive to fully parse and load the DVD's contents before the drive is visible to Windows 8 (E.g. - visible in the File Explorer). Other DVDs are recognized very quickly. I've noticed that this is especially the case with some (not all) DVDs I burn myself, despite the DVDs being run of the mill 4.5GB blanks and were single-session burns.
It appears that if the DVD drive takes too long to "recognize" the DVD a Windows 8 time-out kicks in and an error pops up in the system tray saying "The last USB device you connected to the computer malfunctioned, and Windows does not recognize it". If I go to the Device Manager and right-click the "Unknown device" element in the Other Devices section, I see a "USB\DEVICE_DESCRIPTOR_FAILURE" message on the Details Tab. The only thing I can surmise is that the time-out in Windows 8 is shorter than my older system running XP because on that system the I do not have this problem.
To clear up this condition I have to put a DVD into the Sony drive that the drive can "recognize" quickly and then power off and then on again. Then the drive comes back and is recognized by Windows 8. However, if I put the problem DVD back into the drive, I get the error condition again.
Assuming this is a time-out problem with Windows 8 having only a limited amount of time to get a proper report back from the external drive, is there a registry setting or something I can change to fix this (to increase the time-out value Windows 8 is enforcing for USB devices to report a descriptor ID? If not, has anybody else experienced this problem? None of the information I found through extensive web searches worked for me. I've tried different USB ports on the system, all direct connects and not through a USB port, and I still have the problem. Doing a "Scan for Hardware" changes after the Sony drive appears to recognize the DVD doesn't help either.