I just installed SNAP 4.0 and when trying to start it appears to load but then shuts down unexpectedly. This has not happened before and I noted that my computer updated java yesterday and that other software si behaving strangely too. Thanks for your help.
I’m sorry to hear that. SNAP installs its own Java instance. So the update of Java can’t be the reason for this.
As you said also other software behaves strange it is probably not a problem of SNAP.
Have you scanned your system for viruses or malware?