If you set a region it almost certainly had to read a disc.
You are using something like Nero to burn the discs right?
And something like Power DVD to play them?
Given you can see it with DiscInfo it's almost certainly a software issue.
Can you run Nero's CD Speed utility on DVD-ROM and CD-ROM disc.
Define what you mean by not reading, can you see the drive in Explorer does it give you a drive letter, what happens if you put an Audio-CD in?