external sd - How can I recover the files in LOST.DIR on my SD card, and what are they?

I've always had a LOST.DIR folder on my external SD card, which until now has been empty. Today my phone complained that my SD card was damaged and wouldn't mount it, so I pulled it out and looked at it on my computer. There's now a 70237 file inside LOST.DIR which is 128 MB. It starts with something like "ëWindows 98 FAT boot sector (which makes no sense).

What did Android dump here and and why? (I think I may have disconnected my phone from my PC yesterday without ejecting the drives first, so that might be the "why", though it was from Windows XP and not Windows 98.) Is there a simple way to recover the information in this file?