Thanks Bret. I think I first started noticing the timeout issue occurring frequently last week about the time I applied the Feb 2015 Microsoft patches on the Win7 workstations (and Win2K8R2) I use to access the Moodle. (I haven't had time to test the March patches yet.) This also included going from Firefox 34 to Firefox 36. I wondered if perhaps Firefox was doing something strange, but it also happens in IE.
At this point, I am unsure of the state of the installation, so I reverted my VM to just before the installation. I will try and look for timeout options in php and apache. I'm not aware of anything which should have modified the timeout values, though. I may end up waiting until the next class finishes to try again.
David