I had that same issue. I don't recommend hotswapping your HDD because you can freeze it so it won't work anymore, but the Xbox can't set the date/time or you deleted the Xbox dashboard. What you'll need to do is follow this to get the HDD unlock key (Write it down on a sheet of paper, the automatic way didn't work for me for some reason...)
http://forums.afterdawn.com/thread_view.cfm/357863If you need an Eeprom Reader built, I can make you one and ship it to you, PM me for details.
Then you'll need to obtain the default C drive install from Slayers EvoX Installer and place the files into the C folder under the linux folder.(google for it...might take a while)
After you've done that, download this and run it, selecting the options you want for your softmod. You'll need to place the created Ndure folder in the Xbox HDM/Linux.
KingRoach's Ndure Softmod Installer
http://www.mediafire.com/?oi2td0xpoop4Place this file under XboxHDM\Linux\Ndure, Don't rename it or give it an extension or anything! Make sure it overwrites the one that was originally created, if there isn't an original one there, then you're good to go!
http://www.mediafire.com/?rqozlxthjmrNow run the make iso.bat and burn it to a CD-R. If you're running a Cd drive and the Xbox HDD off the same Cable, make sure you set the HDD to "Master with slave present," it'll make things easier. Now pop in the CD and run the PC bios so the startup is set to CD first and make sure everything shows up! Once you boot up the cd, type in 3 and hit enter to go into the Linux HDD lock/unlock tool. Once you're in that, you'll need to type in this
unlockhd -p (HDD key that you wrote down goes here, no parenthesis)
It should give you a message saying that your HDD was successfully unlocked!
Now type in reboot so the computer reboots itself and then enter the number that says XboxHDM or something like that. Type in Xboxhdm and the yes to the questions, DON'T type just "y" or it will stick you in an infinite loop of the letter y going down the screen. Go to option 1 (NOTE:All gamesaves, music, media will be deleted.) Now it will format and partition the drive if need be. It will rebuild your Xbox HDD. Once it's done, reboot the computer again. Now run XboxHDM again, but this time, type in xbrowser. Go the the *ndure file, it's the file you downloaded and placed in the ndure folder yourself and hit enter. It will bring up a menu. Just choose to soft mod it and follow the instructions on the screen. Once that's done, You'll need to do a hard reset of your computer, I don't think typing in reboot works when in the Ndure Installer! Enter the unlock/lock HD menu again, this time, type in
lockhd -p (HDD Key goes here again)
Now just pop the HDD into your Xbox again, and you should be good to go! After you shut your computer down of course.
Let us know what happens!