Wrong button there -_-
I doubt your ROM is the issue. The first few lines of the logcat while booting would help in working out why data2ext2 isn't working.
The only suggestion I have left it to back up what you can, wipe and start over. In the interest of transparency, there are probably less destructive ways of fixing this; however I haven't used data2ext in ages. I think I stopped using it about a month after I posted it here, so I have no idea how this works any more
To restore your version of busybox just flash your ROM again with no wipe. All your data will be intact (assuming the creator of your ROM wasn't a jerk by putting a wipe in the updater-script). What the re-flash does is restore the /system partition back to default. (Busybox is stored on /system). To reset data2ext run data2ext --disable, wipe /sd-ext then re-enable data2ext, but you lose all your data (I think).