Hi all, I’m stuck with a weird Steam issue on Windows 10 and I’m hoping someone here has seen this before.

Problem

Steam doesn’t open any window/UI. When I double-click Steam, steam.exe shows up in Task Manager (very low CPU/disk, ~tens of MB RAM) but no window ever appears.
Also, steamwebhelper.exe does NOT start, so the UI never initializes.

What I’ve already tried (so we can skip the usual “reinstall” replies)
1) Basic stuff

Rebooted many times

Run Steam normally and as Administrator

Compatibility mode

2) Multiple reinstall / clean install methods (3 different ways)

Uninstalled and reinstalled Steam multiple times

Deleted Steam caches / user data:

%localappdata%\Steam

%appdata%\Steam (if present)

“Hard” uninstall: removed all leftovers from:

C:\Program Files (x86)\Steam

C:\Program Files (x86)\Common Files\Steam

Installed fresh Steam in a different path: C:\Steam (outside Program Files, to avoid UAC/permission issues)

3) Steam Client Service

Checked via sc query "Steam Client Service"

sc start "Steam Client Service" → service starts and stays RUNNING

Still no UI and no steamwebhelper.exe

4) Launch options / flags (no change)

Tried launching Steam with:

-console

-debug_steamapi

-no-cef-sandbox

-cef-disable-gpu

-cef-disable-gpu-compositing

-vgui (still no window)

5) New Windows user profile

Created a brand new Windows user account to rule out profile corruption → same issue

6) Antivirus / security / networking

Windows CodeIntegrity logs showed events involving Kaspersky and Bonjour mdnsNSP.dll

To eliminate that:

Uninstalled iTunes + Bonjour

Uninstalled Kaspersky

Ran netsh winsock reset + reboot

Still the same behavior

7) Logs

C:\Steam\logs\bootstrap_log.txt shows updates/download/verification (“Verification complete / Nothing to do”), but after that Steam just stays “idle” with no UI.

content_log.txt is not even created.

8) Clean boot test

Disabled all non-Microsoft services via msconfig (clean boot).

At one point Steam showed a popup like “Steam Client Service requires maintenance / Install service”, but after reboot it still wouldn’t open normally.

What I’m looking for

Any ideas on what could prevent Steam from spawning steamwebhelper.exe / initializing the UI (Windows mitigations, drivers, overlays, policies, etc.).
If anyone has seen steam.exe running with no UI and no webhelper, I’d really appreciate pointers.

Thanks!