pve dungeon crashes on boss fights

[Wyzard]

Hi since about a week ago I've been getting crashes to black screen on only boss fights in dungeons like

-the BS boss surrounded with a circle of flame (sorry forgot name, he's a giant demon)
-the sigmar crypts boss twins with alternating aura effect


I don't crash for any pvp zones usually but unless i restart computer this crash will continue until i'm forced to restart.
Must end game in task manager to end it.

Let me know if any ideas. The two bosses that crash me seem to have static spell effects in common (the fire and the moving aura on twins).

[Hargrim]

Are you using 64 bit exe?

[Wyzard]

Ya for sure