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This is no bug, Dmitriy, rest assured, but just in case you haven't downloaded the official patch and the Baldurdash fixpack yet, do it now. It fixes a lot of common and annoying bugs.

Your problem, though, is a simple one. I'm assuming Phaere told you to be at a specific place at a specific time, and you weren't there at the given time. Now that's not that big of a problem, the only consequence is that Phaere finds out who you really are, thus revealing your identity to the whole of Ust Natha. That's why everyone turned hostile, and that's why you can't escape.

The solution to your problem, as presented by andrewas, is to kill Matron Mother Ardulace, who resides in the Temple of Lolth (east side of the Ust Natha city map). And remember: facing the consequences of your actions is always more satisfying than starting over (that's my opinion, at least)