So I loaded some TV show videos onto my X last week to watch during the commute and for some reason they went missing after I connected to the laptop to root it last week (I also get a windows error message saying there is something wrong with the SD card and windows needs to scan it but I usually just skip it). So this morning I reloaded some stuff on there and now I notice some video I've taken with the phone is now gone along with quite a few pictures. 
There doesn't seem to be a particular time frame that are gone either. random
Could the SD card be bad? Or is this an issue with windows screwing up something? (windows vista)

There doesn't seem to be a particular time frame that are gone either. random
Could the SD card be bad? Or is this an issue with windows screwing up something? (windows vista)