Do I have to agree to not sue in a Stock Purchase Agreement?

I have a minority share in a closely held family business. Due to a family fight my father chose to buy me out. The company simply deposited the money for the shares in my bank account. I refused the deposit because I had previously asked questions as to succession but the company refused to answer me. I was previously told my father had a buyer and then was told he changed his mind. The difference in selling to an outside buyer or back to the company may be about 2 million dollars. I wanted to know what every other shareholder knew. There''s been alot of lying and I don''t trust what I am being told. However, at the same time I want out. Now I am required to sign a Stock purchase agreement and an Irrevocable stock power. I don''t like the SPA because of one clause that says I agree to release them from any claim whether known or unknown and no matter when arising. I believe this would bar me from suing for fraud. Can they force me?