well, i suppose the most obvious question is what possessed you to use a null password for an encrypted drive? a bit like putting your money in a paper bag, isn't it?
the second question would be; if BT is working and the "other linux" isn't, then why are you asking us?
first thing i would do is change your dmcrypt password to something functional. that may not only solve your problem but actually let your encrypted disk do its job at the same time.....
of course, if it solved your problem, the third question would then arise...but let's not get ahead of ourselves here, ok?
good luck with that.