When in LR transferring, importing, editing my iMac yosemite 10.10.5 just shuts down. No error messages nothing and then computer restarts. Again no error messages. Is this problem with LR or iMac? Gary (email@example.com) Thank You.
A computer cannot shutdown, restart, BSOD/kernel panic, or freeze the entire system due to an application. The only things that can cause those behaviors are bugs in the OS, bugs in low level driver, or defective hardware.
By far the most common cause we have seen is defective RAM (gets stressed by applications that move a lot of memory, like Photoshop and Lightroom).
So, yeah, you're looking at a problem with your system (which Apple techs should be able to diagnose from the system shutdown logs, but most "geniuses" seem to have no idea how to do that).