I was invisible for 30 seconds!

[Master Oake]

I did a quick search and couldn't find anything on this one. After killing Shenk the Overseer (in nightmare), me (a bowazon) my merc, and my amazon went invisible for about 30 seconds. The screen was not locked, and I could see our cursors moving around on the automap, but we were quite "not there". No harm done, and I have to wonder if it was just my graphics chip trying to keep up with the overload bombardment that happens when Shenk dies. I also had two of Mephisto's soulstones- one in the chest, and one on the ground back in Pandemonium that it wouldn't let me pick up. Curiouser and curiouser...