videos do not play when sd card is mounted

[stunmun]

Videos <youtube, websites etc> will not play (only the audio players with a black screen) when my SD card is mounted. Android version 2.3 lg optimus dynamic. If I unmount the card, videos work fine. I am using root but this happens on vanilla or ROM. Any help or suggestions would be great. I only keep music and pictures on the card so I don't know what could cause this.