I suppose, im having a big problem with my MBP i7.
i bought it one year ago, it came with MacOs Lion, i didn't re-install or change anything with the system.
almost one week ago constantly it had booted with kernel panic screen, so i reboot and it's gone, but it came up randomly after and after.
and one day i realized my USB port doesn't work anymore, i tried SD card it wasn't work and it can burn CD or DVD but can't read any of these medias.
and i figured system doesn't mount anything. .dmg, .iso files, any usb storage media, CD/DVD. nothing.
i tried even with hdiutil but nothing didn't work. i can't even install a new system because of this mounting problem.
even updates, can't install them, .pkg files they aren't work too.
and i can't download brand new Mountain Lion which is i already bought.
by the way i have important files which is absolutely need to backup, i can't delete everything on my mac.