I have Windows 7.

I plug in a USB stick containing MP3 files

I open Windows Media Player and select the drive letter of my USB stick, I then see all my music nicely grouped into artist and album just like the MP3 files on my hard drive.

I right-click on an album, hmmm... no 'Play' option - just 'Add to sync list' and 'Delete'.

OK, so I'll try just playing one trac, so I right click a single track - again there is no 'Play' option just 'Add to sync list, 'Delete' and 'Properties'.

So I try double-clicking a track, nothing happens

I can't even create a playlist by dragging the files onto the 'Drag items here' playlist pane.

If I access MP3 file that are on my hard drive then it all behaves as expected - I get a 'Play' option when right clicking an album or a track.

If I open the USB drive in Windows Explorer and double click a track then it plays.

What's going on?

I am at work so could there be a policy that is preventing me doing this?