Hi v3nd3774,
don't worry for your data. As long as it's just a startup problem, your files ar still safe on your HDD.
Anyway, reading the chronology of the events, it could be a conflict with VirtualBox kernel modules at startup, don't know if i'm right.
If you boot from a live system on a USB or disk (maybe the same you installed BackBox from) or if you have another linux distro installed on your PC, you should be able to mount and explore the BackBox filesystem on your HDD, and reach the location in which put "YES" (is it
/etc/default/bootlogd -> BOOTLOG_ENABLE=YES to have startup informations? Can you provide the exact message?).
Good luck!
[little OT] 
This is only a suggestion, and maybe only a personal preference, but it could save you lots of time and troubles. If you have an OS that you are likely to remove or reinstall from time to time (and expecially if you have multiple OS), or you know it's not stable and could fail, you can make your OS run in a little partition, maybe 10GB, and have a big partition in which you store your data and files like books, videos, softwares and so on. In this way if you have problems that you can not solve, you can always install the OS from scratch with no desperation. Another advantage is that you'll have a well defined shared data partition, easily accessible by all the OS you have. Just be sure to format the partition with a filesystem format recognizable by all the OS you are going to install, and use logical partitions if you need more OS.
You should have a thing like this:
+----------------+------+-----------+---------------------------+
| 1st. partition | | | |
| (Windows if | SWAP | BBox | DATA PARTITION |
| you use it) | | | |
+----------------+------+-----------+---------------------------+
Bye, have fun

« Last Edit: March 26, 2013, 11:46:01 AM by b4d_bl0ck »
bool secure = check_paranoia() ? true : false;