WMC empty library folders.

Hi, first post here. Likely to offend some technical wizards with my newbish efforts at describing technical things, but here goes.

I have a relatively new Dell Inspiron 660s. Few months old but have only just got around to setting up WMC on the machine, or trying to. I can navigate fine through the media libraries, the correct folders show up and folder images appear where I have chosen them, but all folders display as empty (0 items). At first I thought it was an issue with attempting to use external hard drives as my media storage, but after restoring all media libraries to default, it seems it's any folder I choose, whether on internal or external storage. The only media library I haven't changed and seems to be working is Music - this is all on my internal drive, loaded onto PC via iTunes.
When I change a media library the "updating libraries" dialog appears and seems to be adding files to WMC, but when navigating the libraries there are no files to be found in any folder - all 0 items.

Incidentally - changing media libraries also seems to change the folders in Windows Explorer. If I add/remove a folder to/from the Pictures library, it also adds/removes it to/from Pictures in Windows Explorer. This is not something I recall happening in Vista.

Totally flummoxed... any help gratefully received.

Thanks ThrashZone.

The problem actually turned out to be something to do with my codecs!?
I found a forum that suggested this issue might be solved by installing the Shark007 codecs as others might not be too compatible with WMC. I installed the Shark007 codecs and this seems to have done the trick.

Hopefully this might help somebody else with the same issue.