On April 26th, Microsoft announced a critical security flaw with the Internet Explorer (IE) browser. The flaw was discovered as cybercriminals were using it to target organizations in the USA. The flaw affects IE versions 6 through 11 on Microsoft Windows. It is not known when Microsoft will provide a fix.
Given the criticality, it is recommended that IE users move to an alternate browser (such as Chrome or Firefox) and also set this as their default browser (Start > Control panel > Default programs).