The issue of unplugging usb devices without ejecting/unmounting them in windows was done away with in Windows 7. Even if it was still a problem, that would normally just impact flash cards and usb drives/ipods(things with accessable storage).
Now, I think this should work, but it involves a lot of steps, so you may want to print this out: *Make a backup of your system, or important settings, and if you have tones saved to your computer. Shouldn't be a problem, but I always recommend doing a backup before troubleshooting.
1) Make sure that you are using an account that has Administrative privilages and, if possible, that the account has full read-write permissions in the registry.
2) Make sure that the following services are enabled: Windows Installer, Windows Modules Installer, UPnP Device Host, and Plug and Play.
3) Make sure that you have the ORIGINAL installation software that was used when you first installed the PODHD500 and it worked.
4) Look for the following files on your computer, making note of where they are originally located:
L6PODHD###.sys( the '#' represents version number of the driver. for example L6PODHD564.sys)
copy these files to a folder on your hard drive, where Windows won't automatically look for drivers. Like C:\podbak
5) Open the registry using regedit. Making sure that the computer icon at the very top is what is highlighted,left click on "File", then "Export" to save a copy of the entire registry.
6) Making sure that NOTHING is plugged into any usb port, use the Line6 uninstaller, or through "Programs and Features" in Control Panel, uninstall everything related to the PODHD install. Yours may just list the Line6 Uninstaller, but if it lists Line6 EDIT and Monkey, uninstall those as well.
7) Reboot your computer.
8) Go into device manager and uninstall EVERYTHING listed in "Universal Serial Bus Controllers". (Windows should reinstall the correct ones on reboot).
9) Reboot your computer.
10) Go back to where you ORIGINALLY found the five driver files, listed above, and delete them(remember, you made backups of those files).
11) Delete the "Line6" folder from the Program Files directory.
12) Go back into the registry and delete the keys related to the PODHD500. Look under HKEY_CLASSES_ROOT. There may still be one or two keys labeled "PODHD500Edit.PODHD500Bundle" and "PODHD500Edit.PODHD500Patch" *Note that Line6 Edit is the SAME for all PODHDs, so it MAY say "PODHD300". Also, if it's still there in the registry after having uninstalled it through Control Panel, delete HKEY_LOCAL_MACHINE\Software\Line6. Since you are using 64-bit, it may be somewhere else(I don't have a 64-bit machine where I'm at right now, so I'm not sure about all your registry settings).
13) Reboot your computer.
14) Make sure that your PODHD500 is turned on but NOT plugged into a usb port on your computer; make sure nothing is plugged into a usb port. Run the Line6 installation software that you ORIGINALLY used to install the POD when it worked.
15) When the installer prompts you to connect the device, make sure to plug it into a USB 2 port (NOT a USB 3). For best results, plug it into the usb port that you FIRST used with the original install.
Again, this SHOULD work. Just remember the specific port that you plugged the POD into upon successful install.Because, you will want to ONLY use THAT port for the PODHD500. DO NOT plug ANYTHING else into that port, and don't plug the POD into any of the others. Techinically, all of the usb ports on your laptop are part of a hub. Line6 products must have exclusive association with a usb's assigned address. This is why Line6 tells you not to use a usb hub.
Best of luck