Hewlett-Packard stock hit a 10-year low Tuesday after the computer and printer leader took an $8.8 billion charge related to its troubled acquisition of software firm Autonomy. HP (HPQ) was forced to revalue the acquisition after discovering "serious accounting improprieties, disclosure failures and outright misrepresentations at Autonomy" prior to the purchase, the company said in a statement. HP revealed the noncash write-down with its mixed