Actually just while this going on what is the current position with the bank accounts and control etc. is there any chance that your partner could help themselves to funds without your knowledge/agreement?
Do you have the funds to pay the 40% you mention? Also, who prepared the accounts as at September 2009 and are you happy that they are fair and accurate etc.
If so just pay her the 40% and say that is what the business was valued at at the date of dissolution. Leave it to your partner to attempt to take the final 10% from you.
In saying that what is the current position with loans etc? The reason I ask is that perhaps it is best to leave your partner hang on in there however get an agreement that from now on you are entitled to a larger share of the profits from here on out but have your partner there to share with liabilities should the business get into financial difficulty.