Update (Feb 10, 16:30 CET):
1, A fix tool that will replace ekrn.exe with a fixed version will be ready within today (Feb 10). The tool will need to be run on machines with affected ESET Security products that are malfunctioning. No restart should be needed to get the product work. The tool should work for affected Endpoint v5 as well as v6.5 products also on Windows XP and Windows Server 2003.
2, If you have an affected version of the product and it still works alright, do not restart the computer yet. Tomorrow (Feb 11) we'll be releasing Antivirus and antispyware module which will patch ekrn to fix the issue.
3, We should have 6.5 installers with a fixed ekrn.exe ready by tomorrow and will replace them in the repository too.
4, After remedying the issue, please consider upgrading to the latest Endpoint v7.2 wherever possible. While Endpoint v5 and 6.5 products will work until they reach EOL, we strongly encourage you to use the latest version which not only addresses bugs and issues from older versions but also brings substantially better protection against current threats.