Julia crashes with new installation on installing a package

I’ve had troubles with Julia 1.7.1 on Windows 10, so just now I downloaded and installed 1.7.2 - as a user, and checked “Add Julia to PATH” as recommended.

The first thing was to add a package or two:

Pkg> add "LinearAlgebra"

This started off OK, then suddenly crashed. And now I can’t start Julia at all. Attempts simply produce the popup window:

"Windows cannot access the specified device, path, or file. You may not have the appropriate permissions to access the item."

I get the same error if I run as administrator.

I see that a previous similar issue was related to the antivirus software CIsco Secure Endpoint, except that in my case Julia is not listed as a quarantined file - and in any case the file is still in its directory, it just refuses to be opened.

Any help would be gratefully received! Thank you.

Just for reference : it’s all fine when I try it

$ mkdir la
$ cd la
$ julia --project=.
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.7.2 (2022-02-06)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

(la) pkg> add "LinearAlgebra"
  Installing known registries into `C:\Users\lenovo\.julia`
    Updating registry at `C:\Users\lenovo\.julia\registries\General.toml`
   Resolving package versions...
    Updating `C:\Users\lenovo\la\Project.toml`
  [37e2e46d] + LinearAlgebra
    Updating `C:\Users\lenovo\la\Manifest.toml`
  [56f22d72] + Artifacts
  [8f399da3] + Libdl
  [37e2e46d] + LinearAlgebra
  [e66e0078] + CompilerSupportLibraries_jll
  [4536629a] + OpenBLAS_jll
  [8e850b90] + libblastrampoline_jll
Precompiling project...
  3 dependencies successfully precompiled in 2 seconds

(la) pkg>

If this is a business computer (as I assume) you should probably talk to your system administrator if what you are doing is supported?