Here's a rather manual suggestion:

Go to the folders on your N900 and 'move' the files from you memory card to the N900 memory. Then 'move' them back to the memory card (if you want to keep them on the memory card). That'll guarantee to view your pictures and media files.

I had that problem recently because I wanted to format my SD card. After reinstalling the contents on the formatted SD, the N900 could not pick up the photos and media files, and I noticed only contents on the N900 were displayed. Which prompt me to try the above manual method.

Note of caution, because I had a lot of pictures, it cause the N900 to temporarily hang and I had to restart it. To my horror, it changed the file name of the N900 to some BCMxxxxxx Initialization Configuration. You can easily reset that through your Bluetooth naming. Ref this thread http://talk.maemo.org/showthread.php...737#post908737