Last week, after the release of Windows 8.1 Update 1, it was reported that one of the primary support calls hitting the Microsoft support desk was a problem where IE11 just stopped working. And, further investigation showed that, in some cases, Microsoft Office applications would fail to start, too.
Over the weekend it was identified that the primary culprit causing this issue is Malwarebytes Anti-malware Enterprise (MBAE). Malwarebytes is a popular antimalware tool, and I guess, the numerous Microsoft support calls on the issue help support its popularity, because the IE11 and Office app problem can be fixed with a temporary patch released by the company.
A new version of MBAE is being worked up to permanently fix the issue, but the company has posted the temporary patch to its forums:
Malwarebytes recently committed support for Windows XP. The 13 year old operating system expired on April 8, 2014.