Besides those two there is also a computers security to consider.
If you have antivirus or similar then it can and has caused some issues in the past.
We would at least need to know what you have for security to be able to help further but in most cases turning OFF the AV just for the download can and has helped people before.
Once that is done it is normally a good thing to add the Arduino install locations to the antivirus exclusions / whitelist. That last step can also in rare occasions help from the start.
Then there is the users security level on some OS where they need to have at least Admin status or privileges.
More often that is of concern where the computer does not belong to the user and maybe on loan from a company or school etc.
In which case the IT departments should be involved to raise the users privileges.
The third scenario is possibly the worst and is when a computer is already infected with malware or a virus.
Depending on how long it has been infected can dictate what steps to take from simply cleaning to a complete OS re-install.
If you have played with multiple IDE’s this has on occasion been seen to cause some side affects (not yours IIRC) but I have attached an IDE clean up document in case it proves useful.
CLEAN UP BEFORE INSTALLING ANOTHER COPY OF THE IDE OR ARDUINO CREATE.pdf (347 KB)