A computer security firm in Finland has detected four new versions of the computer worm that's infected some computers in the United States.
There are scattered problems in Asia and Europe, as well.
A computer virus researcher says there are now eleven different variations of the worm, which clogs networks and reboots its host computer.
It's difficult to estimate how many computers are affected because the worm travels directly over Internet connections instead of through e-mail attachments.
The problems began this month when Microsoft announced a security flaw in its Windows 2000 operating system. Hackers got to work before many companies installed patches to fix the gap.