Hi lfstudios10,
If you are using the original release of ESXi 5.1 (build 799733), note that there is a well-known problem with PCI passthrough disagreeing with certain PCI devices and giving a pink screen... See this KB article. That issue has been resolved in the latest ESXi 5.1 patch release.
If that's not what you're seeing there, a good starting point for troubleshooting is simply to post a screenshot (or a photo) of the pink screen here in the forum.
Cheers,
--
Darius