Hi and Welcome to the Forum,
Can you provide us with the Make/Model of the computer running your Windows7? different brands of computers do different things and each has it's own quirks. Also, it's helpful to know if it's a desktop PC or a laptop with the Win7 so we don't have to look it up.
I'm not familiar with Wow cable, perhaps you are outside the US? However, I've done a few hookups with Roku streaming boxes and Windows7. The next thing is do you have any additional computers or printers in your home also on that same Windows7 homegroup? If you do, I suggest you unplug all of them except the Windows7 computer and your Cable box. Recheck the new Media and see whether the new media is available on the existing shared folders. If it reappears, you'll have to unjoin each and every computer on your homegroup network as well as each and every printer. This is unlikely to work, but it's a starting point.
Next, if this doesn't resolve the problem with just the Win7 computer and the Cable box, you can try some other things. Where did you get the new media content from? This is important because if you downloaded from a P2P sharing like uTorrent or PirateBay; those files; especially the movie files are loaded with viruses.
If this is the case, I suggest you refrain from downloading from those sources anymore, as they have deposited a virus that's blocked any new content from being recognized on your homegroup shares. We call these
"homegroup viruses" now. They are rampant on P2P services. I suggest you run whatever Anti-Virus scanner you have on that computer and remove/delete/quarantine any and all viruses found. Reboot your computer, and try loading a legit media such as a digital movie you got from a blu-ray disc purchased, or a movie your purchased such as from iTunes store and try to share and play those. If either or both of those work, then the virus damage has been reversed, and you can continue as before. If your A-V doesn't find any viruses, I urge you to download and run the free
MALWAREBYTES from malwarebytes.org. This program does a much better job of finding and removing Spyware viruses, of which Homegroup viruses are a subset of, than traditional A-V programs alone.
There is also a well-known quirk with Windows7 homegroups, and this is that if you DO have any other Windows7 computers in your home network, and they were all joined to your existing homegroup and we able to see the shared content on your computer, any time you add a new device or new content to your existing homegroup (your case is new content added), Windows7 on your other computers may not pickup that change by itself without asserting re-ownership of that folder and it's files. Of course, the easy way to do this is simply take computer #2 with Win7 and unjoin and rejoing the existing homegroup. Wait about 30 minutes, and try again to see if the Cable box can see the content. In a home network where ALL computers are Windows7, these issues can occur. If you have even 1 other computer with say XP, Vista, or Win8/8.1 on the homegroup, this situation will not apply. I'm just guessing here, since I don't have a complete diagram of your homegroup network.
If you have no other computers on your homegroup other than the origianl Win7 computer and the Cable box that simplifies things. You can simply unjoin and rejoin the Cable box from the existing homegroup. This could solve the problem.
If that fails, you may need to remove the existing homegroup and recreate it on the Win7 computer. Rejoing the Cable box to the homegroup, add your new media and test it. This may also work.
If none of these work, you may have Windows corruption that can be repaired easily, or a coincidental hardware failure such as a hard drive or RAM memory failure. Post back if you wish help on troubleshooting your hardware, and I can provide you with some free tests. The other alternative is to take it to your local Computer repair shop and pay a Tech to test your computer top to bottom. This usually costs $30-$120 US or so. If they find a faulty component, they will give you a cost estimate to repair it. Once repaired, you can retry your test and see if things work. This is a good idea, since this should eliminate any hidden homegroup viruses you can't find, as well as tell you that your problem is not due to a hardware failure.
In the scenario that the repair Tech finds no viruses or removes any found, and now hardware failures, you can take your computer home and rerun the test. You can then try some of the homegroup solutions I suggested above. If the problem persists, I would suggest a
WINDOWS RESET or WINDOWS REINSTALLATION as a last resort.
If the
WINDOWS RESET or WINDOWS REINSTALLATION fails, I would suspect the Cable box of being faulty, and call and ask them to send you a replacement.
Post back answers to my questions, and let us know how it goes.
Best,
<<<BIGBEARJEDI>>>