Here come the conspiracy theories
After more than 12 years of service, Microsoft finally pulled the plug on Windows XP by ceasing to support the operating system last week. However, Microsoft did promise to keep doling out updates for its Microsoft Security Essentials (MSE) software, including the version that runs on XP, but in doing so, the Redmond outfit only made things worse. That's because the latest MSE update is causing some XP machines to freeze up and run slow.

Anyone with a tinfoil hat will tell you this is entirely intentional on Microsoft's part and nothing more than a thinly veiled attempt to get users to upgrade. The real explanation is likely far less insidious, though equally annoying for XP users who had hopes of holding onto the legacy OS for at least a little while longer.

"I am a professional computer engineer and maintain many desktops and laptops for my customers on a daily basis: as of today (April 16th) I have seen about 12 computers on which Windows XP - after every boot up - throws up an error message referring to MSE, stating: 'MsMpEng.exe application error. The instruction at 0x5a4d684d referenced memory at 0x00000000 The memory could not be read', leaving the computer in an unusable state," a user wrote on Microsoft's Windows forum.

He goes on to say that "the only solution is to disable MSE or uninstall it completely." Doing so will restore performance, but it comes at the expense of security protection, which is now more important than ever for XP users.

Microsoft has yet to acknowledge the situation or issue a fix. One is likely coming, but in the meantime, there are third-party AV vendors that still support XP.