SAN FRANCISCO (Reuters) - Computer security experts said on Thursday the recent "SQL Slammer" worm, the worst in more than a year, is evidence that Microsoft Corp.'s year-old security push is not working. "Trustworthy Computing is failing," Russ Cooper of TruSecure Corp. said of the Microsoft initiative. "I gave it a 'D-minus' at the beginning of the year, and now I'd give it an 'F."' The worm, which exploited a known vulnerability in Microsoft's SQL Server database software, spread through network connections beginning on Saturday, crashing servers and clogging the Internet. It hit a year and one week after...