@gmoises Perhaps hardware acceleration (GPU), extension or security tool blocking a library.
For a check, start without extension and hardware acceleration
Linux: vivaldi --disable-extensions --disable-gpu
Windows: start vivaldi --disable-extensions --disable-gpu
If that fails check if new profile starts
Linux: vivaldi --user-data-dir="/tmp/TESTV"
Windows: start vivaldi --user-data-dir="%TEMP%\TESTV"
If that fails: Reinstall Vivaldi with installer file from vivaldi.com