My Macbook 5,1 died unexpectedly the other day -- the LCD screen dissolved to white and would only show white on subsequent reboots, although i could hear MacOSX booting up in the background. After resetting the SMC and NVRAM (as suggested on OSX forums) it stopped booting up at all. I took it into the Mac store and they told me that rEFIt (v0.12) screwed up my EFI and they had to replace the logic board ($1000). I don't know if this is true -- I rather suspect that it was something else and they took the opportunity to blame rEFIt because it is unsupported software that invalidates the warranty! Thankfully the manager was merciful and fixed it under warranty, but I thought I would let people know that if they want their computer to be fixed under warranty they should remove rEFIt as soon as possible and just let Bootcamp load their Ubuntu OS so that the technicians can't blame warranty-covered problems on rEFIt.