mine use to do the same thing.
Try uninstall and re-installing sansa media converter. Mine was an ArcSoft version(it said it when I opened it up). I was told I could uninstall it and remove ArcSoft from the registry and try to install it again. Removing it from the registry wasn’t too hard, but I wouldn’t suggest it for the less computer savy as you could POTENTIALLY mess up your computer big time.
All I did was CTRL+F for “find”, and found the work Arcsoft to delete it. It was the only program I had installed by arcsoft so I just deleted the whole thing. And reinstalled it and it worked fine.
I had an ArcSoft version of the sansa media converter and SanDisk sent me a new CD with Intervideo version. And that one works perfectly fine too. Seems they sent me the CD after I got it working, but I prefer the intervideo version anyway.
You can still put pics and vids on the player even if SMC(sansa media converter) doesn’t detect it though. You can leave the player disconnected. Convert whatever pics or videos you need to convert. They go to a folder called My Documents>Sansa Media Converter by default. Once you find them in there you can drag and drop them onto the player itself.
Hope this helps.