So, I just entered Dustman's Cairn, and halfway through it, all of the textures are flashing this light teal blue colour. Can anyone help with this?

I just got tru that same place today and I had the same problem. It still continued when I left the crypt too. I tried saving and reloading but it did not fix it.

I've been having the problem with a neon green-blue texture error as well. I'm trying to post a tread about it.

When out in snowy mountains, or walk into new towns, even bringing up menu in water and then going back -
I end up with a very flicker-ish (and sometimes in chunks and pieces) setting that scratches-and-flickers a neon green-blue?
I remember this problem with Fallout 3 once in a while. Color is similar to the Pepboy txt. Only it would vanish when you enter a location and come back.
Sometimes it's EVERYTHING - for instance when doing Daedra Quest for Calvicus Vile and in a cave,
the entire cave will flicker all over consistently in chunks and pieces and remain neon green-blue until I leave.

possibly linked?

I've had this happen on two occasionson 11/11/11, first time at Dustman's Cairn. . Don't believe it is a console overheat issue., mine has additional auxiliary cooling fan. Not specific to one dungeon though... and if you leave the dungeon, the effect continues while traversing above ground. Solution is to shutdown console and then re-start at saved point. You CAN save at the point where this bug starts, reboot - reload , and all will be good! However.... I had it re-occur about 7 hours of gameplay later, different dungeon. Took it as a good time to take a game break and give the console a rest. Played 8 hours yesterday, but had no re-occurence.

Update: I saved the game, and restarted the console, and this seemed to fix the problem. It happened again, however, some time later the next day (in some dungeon during the thieves guild questline) and I solved it the same way.