Vista explorer can’t read a DVD (unknown format) but DIR command can do it!

I was trying to install Visual Studio 2008 from a DVD but exporer fails to read the disk ( unknown format ) asking me to format it instead.
I’ve tried with CMD and DIR command and I have succeeded starting the setup and reading the directory tree, but the setup stops asking for existing files that explorer can’t see.
The PC is a new HP Pavillion and the problem exists with all the cd/DVDs.

I could xcopy from the DVD to my disk but this situation seems to me quite nonsense.

Any idea? Thanks.