What are your auto-reload settings? (Tools > Options... > File Options > Load > Auto Reload)
There was a bug fixed regarding auto-reload, but it involved the case where you get an auto-reload prompt and hit Escape to dismiss it. The bug was that it would come up again, even though you had dismissed it (even though the file had not changed again on disk). But maybe there is a special case with whatever settings you are using that causes the new logic to break.
Also, is the file on a remote drive?