For sure answer hobo10's questions. I also wonder if that DVD drive of yours is getting old.
Almost seems like the whole computer isn't refreshing or isn't refreshing fast.
How much RAM memory does your system have?
How much unused space on your hard disk drive?
Are you using a newish, fast computer? What version of Windows are you using?
Did you just update your Windows Media Player(?) or download service updates from Microsoft?
Next time it happens, in between when your DVD is unrecognized but before you reboot, try this. If a drive or software can't see the original, members sometimes have suggested to use a computer based player like or similar to "PowerDVD" to try to play the movie for a few minutes to kick-start the DVD drive. But you say the drive doesn't even flash ... right? Test by turning AnyDVD both on & off and then see if you can use your player software to play the movie.
Sorry all the questions, need to know more.