Software giant Microsoft is to end support for its Windows XP operating system today, leaving one in every ten computers in use in Ireland vulnerable to viruses and hacking.
Microsoft Windows XP was released in 2001 and over its lifetime became a hugely popular computer operating system.
Like most software makers Microsoft over the years released updates for XP which patched holes in the code as they arose.
But today it will end that support for XP, meaning any vulnerabilities discovered by hackers will from now on not be fixed.
According to Microsoft and most IT security experts that will leave internet connected PCs running on XP vulnerable to attack.
Windows XP remains the second most popular operating system in the world and still runs on 10% of computers in Ireland as well as the vast majority of ATMs.
Banks say they have taken steps to protect those ATMs, but other business and home users must either upgrade their operating systems, their computers or disconnect from the internet in order to avoid the problem.