Recentlyv i purchased the house in Windhelm. I wanted to place my blades armor on one of the mannequins but when i put it on it, it becomes invisible is this a glitch?

Yes, it's a glitch. AFAIK there's no fix for it at the moment, but check the bugs forum to be sure.

Just wait until they start to http://www.youtube.com/watch?v=GFKa9tQqzrs&t=1m30s...

Yeah i can't place my weapons on the '' weapons holder '' or whatever its called really annoying

What's really strange is that my weapon racks work just fine in my house in Whiterun, but the Solitude racks are all screwed up. Unfortunate too 'cause the house in Solitude is awesome. Oh well, maybe next patch. Still loving this game though.

Half the stuff works and half doesn't. It's hit or miss. I can't see why that would have been hard to catch during "testing" of the game.

Same thing happens to me in the Solitude house. Playing on PS3 and that's one of the things I hope gets fixed.

The fix to the mannequin is this: Put all your armor on it, and then a random ring. Back out, and it'll all be invisable. Go back into its menu and take the ring off, and your armor should appear on it.

This is interesting because the weapons rack in my Whiterun home doesn't work, but the ones in my Solitude and Markarth homes work as designed. Hopefully these bugs will be squashed in 1.04, but I'm not holding my breath.

Yes! This is happening to me in Riften and it scared the hell out of me. I used the console command player.placeatme to add an apothecary satchel to the alchemy table and when I turned around, the two mannequins were in different parts of the room. I thought it was because of some kind of displacement of the items in the room but i don't know the console command yet to remove the apothecary satchel again. I've been meaning to ask someone. It's too funny...I just keep walking around them. You activate them by pointing to where they should be standing though.

How do you get the mannequin for Whiterun?

Did you remember to click the "deactivate invisibilty" button under the bed?

I wonder how hard Weeping Angels would be to mod in. Detecting whether anyone sees them or not would be the trick, though perhaps the stealth code would do the job.

There is no mannequin in Whiterun. They're talking about the weapon racks.

Well it happens in every house and I think the reason is that depending on which weapons you put on the racks, the ones to it's left or right become unusable because the weapon you put on the rack prior blocks the active area to where you can place a weapon on it. I had this problem in Honeyside, but rearranging my weapons ending up fixing the problem. It isn't so much of a bug as it is lack of accuracy of the targeting I think.
Discovered this on accident, but even then it is only temporary. This is the #2 bug that I have wanted fixed since I discovered it, second only to the bug involving "Blood on the Ice," which drove me to near insanity restarting the same character 2 times before I got the quest to even activate. Plus, I roleplay, and just strutting into Windhelm after the tutorial doesn't make sense to me just to check if the quest will activate.
However, I discovered that if you go into Windhelm, ask Lonely-Gale about the murders, then leave (not immediately if you don't want to) and come back at least three days later, then the body will be discovered in the cemetery. I am assuming it is three in-game days due to what the wiki says, but I actually stayed out several weeks after first entering and leaving