Is it just me and a few other people. . .
I can confirm that it has something to do with a Steam update. I just ran Portal on my laptop, to see how my new map would run on another system. I have only installed portal there, and Steam is set to offline mode. Everything worked fine, until i went online and Portal got updated, then various model animations (a.o. the elevator doors) stopped working.
Tomorrow i'll see if i can get through to Steam support to get them to fix it.
Other Portal 2 maps: Medusa Glare
Portal 1 maps: Try Anything Twice | Manic Mechanic
Tomorrow i'll see if i can get through to Steam support to get them to fix it.
If that's the case, then steam should be able correct the problem. I would assume that they would need more than one e-mail to consider doing anything about it. I'll contact them tonight.
I've noticed that some of my areaportals refuse to close... Though I've had that problem for a long while now...
-Steam Admin.
The more you give, the less appreciated it will be received.
Fixed now 
.
For me, the "verify game files" option that Steam has solved the problem. It's not easy to find, so i've made some screenshots:
First, right-click on the game that has problems:
Choose Properties. On the properties window, click the Local files tab:
Then click on Verify integrity of game cache...
It will look through all files for that game and fix / update things.
If you have multiple troublesome games, you probably need to do this for every one of them.
Other Portal 2 maps: Medusa Glare
Portal 1 maps: Try Anything Twice | Manic Mechanic
[color=blue]One day, my Xbox version lost all the skins to everything except the walls and the floor.
Chell, the cubes, the turrets and even GLaDOS was made up of rainbow pixels. 0_0
It was probably because of the hardware failure,
because a few days later I got the RROD.
I have experienced these on my PC version as well.
But after a few plays, these would vanish. 😐 [/color]
Definitely hardware there Amanda.
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