Hi, been reading tutorials and threads on xbox scene the last 2 weeks since I decided to mod my xbox. Anyway first time to post and yes it's cos I've run into a problem

. To cut a long story short after a failed attempt at a hot swap got a guy who I know sort of from another forum to do a hard mod, replacing the existing hd with an 80gb drive and installing xbmc as well. Just got this done Thursday night and spent Friday evening and Saturday morning ftping a load of movies & music across from my pc.
Had watched a few divx's Friday night no problem but yesterday ran into a wall. Went into settings and checked the option to load subtitles from rar's and started a movie I'd transfered onto the hard drive, no problem at first, but then went to fast forward past the credits when it froze. Screen looked like I'd pressed pause, still had the time counter displayed up in the left hand corner but stuck at where I'd fast forwarded to.
Tried stopping the film, backing out of it, going to main menu none of which worked so decided tp reboot. On restarting I get as far as the xbox logo and that's it. Can hear a sort of rhythmic clicking coming from the box, think it's coming from the hard drive, but I don't get any error codes displayed.
I'm tried starting the xbox with a game and that works, goes straight to the game menu, but the minute I take it out I'm back to the logo and clicking sound.
Any help would be really appreciated, only had the thing for a day and miss it already!!!
Cheers