Cinema 4D 2026 UI turned bright yellow/orange — it's the NVIDIA overlay, not a virus
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 Today I opened Cinema 4D and the entire interface had gone bright yellow and orange (screenshot attached). Menus, timeline, Attribute Manager — everything. It looked exactly like a Windows high contrast theme, but I hadn't changed a single setting.
I panicked a bit and assumed it was malware, since I hadn't installed anything new. I checked Windows High Contrast (it was off) and was about to wipe my C4D preferences folder when I found the actual cause:
It was the NVIDIA App overlay. It had enabled itself automatically, most likely after a driver or app update, and it was drawing a layer on top of the Cinema 4D window that completely broke the interface colors.
The fix:
Open the NVIDIA App
Go to Settings
Turn off NVIDIA Overlay
Restart Cinema 4DThat's it. Colors went back to normal instantly.
Posting this because every search I did pointed toward viruses or corrupted preferences, and nobody mentioned the overlay. Don't delete your prefs folder before checking this — you'd lose your layout and shortcuts for nothing.!!