Hi @mark.lilley,
Thanks for posting your question in the Forum.
Here are a couple troubleshooting steps we can do to find the cause of the problem:
1. Could you may check the release date of your graphics driver? It might need to be updated with the link here:
Nvidia / AMD
2. Could you may try to do the "clean uninstall" with the link here?
https://knowledge.autodesk.com/support/fusion-360/troubleshooting/caas/sfdcarticles/sfdcarticles/How...
3. Would you may share your Log files with us? We could analyze what happens in the background when Fusion 360 is launching.
How to manually collect the Log files is explained in the knowledge article here:
https://knowledge.autodesk.com/support/fusion-360/troubleshooting/caas/sfdcarticles/sfdcarticles/How...
4. It would be great if you could share your system information with us as well.
https://knowledge.autodesk.com/search-result/caas/sfdcarticles/sfdcarticles/Obtaining-system-informa...
I hope this helps. Please, keep us updated.
Thanks,