The FBI has opened an investigation after the Colorado Rockies claimed an "external, malicious attack" on computer servers brought down the club's first attempt to sell World Series tickets. Computer servers handling the online-only sales were overwhelmed by 8.5 million hits in the first 90 minutes Monday, paralyzing the system and forcing the Rockies to suspend the sale. "We are going to be opening up a case looking into the possible compromise of the Web server in Irvine," said Laura Eimiller, a spokeswoman for the FBI in Los Angeles.