Graphics Mode and problem with running diablo

[Jackal_pl]

Hi,
Next problem. I played some time (I finished the normal mode) and today I can't run Diablo. Few days ago I changed mode to the Glide and I couldn't run the game (arror changed into circle for a few seconds and nothing happened). So i changed back to 3d mode and played again. Now the problem is same, but now I can't change the graphics mode! Even if I do Graphic test ticked mode is GLide and when I change mode and confirm it by OK, and the I run again test ticked mode is again Glide.
Sry for my English (or rather Ingrish :)), but I hope that everything is understandable.
What shall I do?

[Etheninex]

Wich graphic card and how old is the driver ?

[Jackal_pl]

Asus HD4870
Drivers are updated automatically. No problems with other games.
I can't change the graphic mode and that is the greatest problem.

[Etheninex]

Did you start as administrator ?

[ChaosEmpire]

If you rename this file

glide3x.dll

Diablo cant find Glide anymore and needs to fallback to DirectX

[Jackal_pl]

As a admionistrator, graphic test and a Diablo 2
@Chaos Energy - well, I renamed it, chose Direct mode, and problem still exists. Well I think I need to reinstall.
Thanks for encouragement.