NEW YORK (AP) -- Nervous calls to computer support lines dropped off sharply Saturday after two frenzied days of combat against a software bug that attacks with the speed of the Melissa virus and the destructiveness of the Chernobyl.
Computer experts, however, feared that the spread of Worm.Explore.Zip will pick up again when employees return to work Monday, adding to the tens of thousands of machines infected with the file-eating bug.The virus, first detected June 6 in Israel, did most of its damage on Thursday and Friday, infecting computer systems at several big corporations.
Federal authorities were investigating the origins of the bug, but offered no details of their probe on Saturday.
Worm.Explore.Zip combines the worst elements of the two viruses that swept across the Internet earlier this spring, using e-mail trickery similar to Melissa's to overwhelm computer networks and attacking computer users individually with the Chernobyl-like destruction of their computer files.
The virus disguises itself as a timely e-mail reply from an acquaintance, inviting the recipient to open an attached file that sends the virus worming into each computer's hard drive and ricocheting around companies connected to that machine by a network.
One of the worst hit was airplane maker Boeing, which was still assessing the damage on Saturday. The "vast majority" of the company's e-mail system was back in operation, said spokesman Dave Suffia. Other big names affected included Intel, Microsoft, General Electric, AT&T and Compaq Computer.
With Melissa and Chernobyl still a fresh memory for most, computer systems managers reacted quickly when word of Worm.Explore.Zip began to spread by Wednesday, possibly helping contain the outbreak.
But for computers already affected, there wasn't much optimism that lost files would be retrieved.
"A lawyer called Thursday evening and said the virus destroyed a bunch of his files. He had to be in court Friday morning and, needless to say, he wasn't happy," said Barry Raven, a technical support analyst for the software maker Network Associates. "Once they're destroyed they're probably not recoverable."
Anti-virus workers reported Friday and Saturday that the momentum behind this outbreak, though very heavy, seemed to be slower than with Melissa.
Although calling volume was four times heavier than normal on Friday at a Network Associates facility in Texas, it was also just a quarter as heavy as the volume during the Melissa outbreak.
The telephone lines were almost silent Saturday morning at the center, dropping off from about 800 customer calls on Friday to just a handful by early afternoon Saturday.
"Yesterday we were bombarded, we had calls right up until the close, but it's dead right now," said Raven, cautioning that the sharp dropoff could prove fleeting when people return to work on Monday and turn on their computers. "There are a lot of people who don't keep up with the news and haven't found out about (the virus) yet, and others who, for one reason or another, decided to wait."
The virus is known to attack only those computers using Microsoft operating systems Windows 95, Windows 98, and Windows NT. Rival operating systems such as Macintosh and Unix apparently are not vulnerable.