Lightroom Classic Not Opening on Windows 11

I have a camera club member with a serious issue opening their existing catalog in Lightroom Classic on their Windows 11 laptop.  Been struggling with the issue of LRc not launching (although running in the background according to Task Manager).  I have completely removed all Adobe products and re-installed Lightroom Classic and have been able to get it to lauch properly.  I have successfully created a new Test catalog and improted a handful of photos into it BUT the moment I try and open their catalg (which is about 395Mb in size) the problem with the launch failure starts up again.  Any suggestions as to what might be the issue with the catalog that is causing this problem and if it can be corrected (OR should we restart the import process with all their photos once again into the Test Catalog that I created?)