Reported by: A Cowork AI OS student, May 2026.
Anthropic bug report: Submitted to Anthropic separately by the reporting student.
Symptom
Claude Desktop runs but fails silently on Windows — prompts go nowhere, no error message, no visible failure. Cowork tab loads but won't respond.
Root cause (as reported)
A conflict between Malwarebytes Real-Time Monitoring and Claude Desktop sets an internal flag inside Claude Desktop. After the AV conflict is resolved (e.g., AV is paused or whitelist updated), the flag does not clear automatically, leaving Claude in a failed state until manually reset.
Possibly affects other active antivirus tools beyond Malwarebytes — only Malwarebytes confirmed in this report.
Workaround (confirmed working by reporting student)
- Close Claude Desktop fully (tray icon → right-click → Quit — closing the window isn't enough).
- Disable / pause Malwarebytes Real-Time Monitoring (or the active AV's real-time component).
- Restart Claude Desktop.
- Optionally re-enable AV after Claude is confirmed working.
- The reporting student permanently resolved this by switching to Windows Defender only (removing Malwarebytes' real-time component).
Why this is on Anthropic, not us
Claude Desktop is Anthropic-owned. The internal flag behavior is inside Claude Desktop, not in any plugin. Cowork AI OS does not interact with the flag. We're documenting this because students who hit it will likely look in our troubleshooting first.
Status
- ✅ Documented in the README troubleshooting section (commit 531d122 on main).
- ✅ Bug report sent to Anthropic by the reporting student.
- ⏳ Waiting on Anthropic-side fix.
If you hit this
- Try the workaround above.
- Comment on this issue with: OS version, AV brand + version, whether the workaround worked, and any other symptoms.
- That helps confirm scope (Malwarebytes-only vs broader AV conflict).
Won't-fix scenarios
This issue is not closed until Anthropic fixes the flag-not-clearing behavior. Switching AVs is a workaround, not a fix.
Reported by: A Cowork AI OS student, May 2026.
Anthropic bug report: Submitted to Anthropic separately by the reporting student.
Symptom
Claude Desktop runs but fails silently on Windows — prompts go nowhere, no error message, no visible failure. Cowork tab loads but won't respond.
Root cause (as reported)
A conflict between Malwarebytes Real-Time Monitoring and Claude Desktop sets an internal flag inside Claude Desktop. After the AV conflict is resolved (e.g., AV is paused or whitelist updated), the flag does not clear automatically, leaving Claude in a failed state until manually reset.
Possibly affects other active antivirus tools beyond Malwarebytes — only Malwarebytes confirmed in this report.
Workaround (confirmed working by reporting student)
Why this is on Anthropic, not us
Claude Desktop is Anthropic-owned. The internal flag behavior is inside Claude Desktop, not in any plugin. Cowork AI OS does not interact with the flag. We're documenting this because students who hit it will likely look in our troubleshooting first.
Status
If you hit this
Won't-fix scenarios
This issue is not closed until Anthropic fixes the flag-not-clearing behavior. Switching AVs is a workaround, not a fix.