The memory I have bought is similar to
this.
Tonight I have tried my 4 gb memory on sony s40 camera and work great.
It works on my usb adapter, but it don't work on prs-500.
I have formatted it in fat32, but nothing.
tonight I have tried another memory stick pro duo magic gate of 512 MB in my prs-500.
It works great.
you say prs500 supported a 4 gb memory stick pro duo.
Then I don't know what my problem. my memory seems ok.
I think I will resell my 4 gb memory stick and I will buy another a 2GB memory stick pro duo magic gate.