There are many stylistic PCs with this problem: grey dots BEHIND the screen...
Last weekend I tried to open my tablet! It's quiet easy - but be careful...
Tomorrow I will do it again... better clean TFT first - then the covering clear screen, otherwise you will collect dust again !
I will also use a professional TFT cleaning gel and a pressure air can...
Video:
http://www.youtube.com/watch?v=d2ial5i6X4M&fmt=18
Good luck!
Sascha