Further to this, now some of the menu items, such as 'Save copy as...' are greyed out and will not work. However, on a restart of the database, they work again. Mitch
You might try sending them a new copy of your run time to test. A crash can damage a file and damage to a file can cause a crash, so you'll need to see if damage to the file is an issue here.
Also, it's not unheard of for a damaged file to appear to function normally until installed on new version of the OS or opened with a newer version of the database. Thus, latent file damage is also a possible factor here--though not the most likely issue here.