Windows Task Scheduler & Intune/Defender issues after recent updates

Hey everyone,

New to the forum hoping someone can guide me in the right direction.

I’ve been troubleshooting a strange issue in my environment over the past few days that’s affecting a large group of users, and I wanted to see if anyone else has run into something similar or has suggestions for a fix.

I have open cases with Microsoft support, but so far there’s been no resolution.

For context: our primary antivirus is CrowdStrike Falcon, but we also run Defender in EDR block mode (which we’ve since turned off, along with tamper protection, to avoid interference during testing).

Back in January, Defender ASR rules were pushed from Intune in block mode. They never caused problems until these recent updates. Those rules have since been set to audit mode in Intune.

Last week, a few Windows updates rolled out (including Defender definitions and security updates). After rebooting, we started seeing widespread issues across many—but not all—devices (laptops and desktops):

Task Scheduler appears broken or corrupted. The app won’t load, and the service refuses to start. Sometimes we see “local computer cannot be found”. As a result, anything relying on Task Scheduler fails.

Intune syncs don’t work. Manual sync from Work/School settings either stops silently or throws an error. The last successful sync on affected devices shows as the last reboot. Pushing syncs from the Intune portal has no effect.

Startup apps (OneDrive, VPN client, etc.) take much longer to load or sign in after reboot.

Office 365 apps sometimes prompt for repair, then work briefly before crashing. License checks in the apps fail—likely because Task Scheduler is broken.

ASR remnants: Some devices still show block rules applied, even though we flipped the policies to audit. Likely because the Intune sync agent itself is broken and can’t pull updated policies.

What I’ve tried so far:

Uninstalled CrowdStrike ..no effect.

Ran DISM and SFC .. no effect.

Booted in Safe Mode / Diagnostic Mode .. no change.

Reset Defender components via PowerShell .. no effect (even with Defender fully disabled and ASR rules off).

Confirmed ASR policy enforcement is inconsistent across devices.

At this point, I’m trying to determine whether this is:

A Windows bug introduced by recent updates,

An Intune policy misconfiguration that corrupted Task Scheduler, or

An interaction between Defender/ASR and CrowdStrike.

So far, the only reliable fix has been a Windows 11 reset (keep files)—which we may have to roll out broadly if there’s no better option.

Has anyone else seen Task Scheduler, intune sync, etc. breaking like this across multiple devices recently? Any advice on how to fully reset/fix it (without full rebuilds) would be hugely appreciated.

Thanks in advance!

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TL;DR:
After recent Windows + Defender updates, intune sync, Task Scheduler is broken on many devices in my Intune/CrowdStrike environment. Symptoms: scheduler won’t start, Intune syncs fail, startup apps are delayed, and Office apps crash. Tried SFC/DISM, safe mode, uninstalling CrowdStrike, and resetting Defender—no luck. Only fix so far is a full Windows reset. Anyone else seeing this or know how to fix without rebuilding?

You say Windows reset - Reset Windows 11 PC - ElevenForumTutorials
Wouldn't a Repair install be less drastic [and would not prevent you doing a reset later on if necesssary]? Repair Install Windows 11 with an In-place Upgrade - ElevenForumTutorials

Might ChkDsk help in cleaning up beforehand in case disk-file corruption is involved? Check Drive for Errors with ChkDsk - ElevenForumTutorials


All the best,
Denis

Techtronic,

I'm very surprised that I did not include a summary guide to the forum in my first reply.


Denis

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Welcome to ElevenForum.

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@Techtronic99

Well you don't have a run of the mill normal situation there. A School I presume with a lot off students and trying to keep things together. Now there is a problem. You mentioned your "build"; 24H2. Yes that's Windows 11 but not the build. It should be like 26100.xxxx I also received the latest update 26100.6584. (Run winver) At what build are you sitting? When did the problem started? After an MS update?

But your circumstances are different. You bought Defender EDR; a Managed Security Platform in endpoint protection, detection and response. An addition we normally don't have. In addition CrowdStrike Falcon a product that is not that widespread.

You placed your problem with Microsoft. I would place it at the Defender EDR company (Huntress). It's their product that has problems with the latest standard update from MS. They designed it and placed it onto the market. Their the ones who would give you a quick solution rather then here. They have also internal short lines within Microsoft to address the problem. I can't image that other users (with the same product) don't have these problems also. The maker of the product will and should know this by now. You ruled out it is a CrowdStrike Falcon problem because you uninstalled it to no reveil. So the problem must be at Defender EDR. (All they have to do; simulate the problem with also downloading the latest patch from MS. All the product needs now is a patch for Defender EDR)

I would first check some online anti virus checks from other anti-virus company's (F-secure, Trend Micro etc.) to rule out your main system and some student laptops is not affected by some virus etc. I hope you don't have a FTP server running to the outside world that is not that well protected. They could invade your network and play tricks. Also if students are not at school how do they connect to your network from home?