I answered a question recently about problems using a flash drive on an old Windows 98SE computer. The individual had the right driver for Windows 98SE, but his computer still didn’t recognize it.
The problem is that USB devices are not consistent in how they must be installed. Sometimes, the answer is to plug in the USB device and then put in a floppy or CDROM when the installer asks for the driver. Other devices require that the driver be installed before you ever connect the device.
With Windows 98SE, some flash drives required that their driver be installed before you ever plug in the device the first time. PNY is one of those, but not the only one of those.
With one of the devices that requires the driver first, if you plug in before installing the driver, Windows sets itself to know ABOUT the flash drive but to know NOTHING ABOUT it.
The fix is to plug in the flash drive, go to Control Panel, and then to Device Manager.
You should see the flash drive there, perhaps with a yellow exclamation point beside it. Select the flash drive and “Remove” the flash drive from Windows (not from the machine, yet, but from Windows using the options available there).
After “removing” it from Window, unplug it from the machine.
Install the driver program (assuming this was PNY)
Plug in the flash drive — and it should be recognized now.