Wife can't get through red portal in Durance lvl3

[Marker]

Help! My wife and I are playing D2 over a LAN and got as far as the Durance of Hate level 3. After we killed Mephisto my character was able to go through the red portal into Act IV, but her char can't get through.
We tried stopping/restarting in different combinations, her hosting, me hosting, etc. ... nothing worked. Any ideas??