so today I just updated to lion everything has gone perfectly smooth except for... I went to go back up my hard drive after doing some work in lion. so as usual booted up my external HD and got ready to hit "Back Up Now" I did so then waited around for quite some time with it saying "preparing to backup" so I waited and nothing happened unfortunately. so I tried later and same issue. so now I'm stuck with this problem.... my external HD had been backing up this mac for some time on osx snow leopard. now my issue is that it just doesn't seem to get past the "preparing to backup" phase. now is this normal for it is a new operating system and that it will just take some time on the initial backup? or is there a problem? do I have to clear this HD and re partition it then set up a new time machine???