So normally you end up only being able to do four quests before the Valsharess attacks. I
suspect the problem is a bug with the Illithid quest, which has quite a few bugs in it. After you complete this quest, the Valsharess attacks.
Both workarounds require the Relic of the Reaper, as well as Rogue Stones. The game isn't too difficult, and there are plenty - you should have around 10 or so in Chapter 2.
One - if you can't enter the Elder Brain's room without being teleported to the "mind realm", and you've already beaten all the monsters. This happens when you betray the Elder Brain. Create a Binding with the RotR and then get teleported. Use the RotR to leave, and go back to your Binding. That will have triggered the... er, trigger, which only activates once and then is destroyed. You should be able to enter the room easily.
Two - you can't get back into the Drow city after the Valsharess attacks. Again, I
think this is caused by completing the Illithid quest. Again, create a Binding in the city before you leave.
DO NOT place it in the Temple of Lloth, because the Seer will corner you and automatically start the battle. Use the Relic whenever you need to get back into town.
Three - you can't talk to the girl you rescue from the Slave Pens. Caused by the above. Also note I've had my henchmen wig out and kill her as soon as I save her. Valen has issues, apparently.

She's in the Seer's room, so as soon as you get there, pause the game, find the girl, click on her to initiate dialogue, unpause.
Hopefully you can reach her in time to complete the quest, earning you 500 experience. You won't get to read the dialogue.