RE:Can we sue Walter?
Yes, that's what the Shareholder Class Action discussion is about. In fact the shareholders can sue all of the Directors and Officers (D's & Os)jointly and severally (ie as a group and individually).
The Board of Directors of a company has to approve the financial statements and "managements discussion and analysis" (MD&A) which is also filed at the same time as the financials. If these documents contain misrepresentations of fact then the Directors breached their fiduciary duty to the shareholders. You are all going to get used to hearing these terms.
For good measure you should add the Auditors, PriceWaterhouseCoopers, to your suit. Nice deep pockets there guys. They do not have to audit the quarterly financials but it is customary to review them and given the state of Tuscanys financial helth at the time, I would be suprised if they did not review them. They should have pushed for an impairment charge, but obviously did not.