Same! I've tried the community, kde, and xfce isos on a second drive and have yet to achieve a bootable system. I'll probably tinker with it a bit more this weekend since Manjaro sounds like the perfect distro for me, but I'm getting close to giving up :/
Installing Manjaro as a second OS and think bricking is a large possibility, I'd bet you have a UEFI install of Windows and used a crappy USB writer that doesn't allow for UEFI.