Thousands of people may lose internet service on Monday unless they check their computers for malware that could have taken over their machines a year ago.

The number of infected computers is probably more than 277,000 worldwide. People with infected computers will have to call their service providers for help deleting the malware.

The problem was caused by international hackers who took control of 570,000 computers before the FBI broke up the operation. People can see if their computers are infected at