Visto on the rocks?We've been hearing dark rumblings about e-mail mobility corp Visto, despite the company's securing $51 million in further investment this past September, plus another $7.7 million in a patent infringement case in December. Unfortunately, Visto's litigious nature — the December victory was only the latest in history of lawsuits — may have alienated a raft of potential acquirers and/or investors (the September round is said to have come mostly from insiders). Otherwise, a high burn rate has eaten up more than $250 million, and a financial come-to-Jesus moment could manifest as soon as early spring.