ora-600 - I guess you know what that means?
To be more precise, 'Internal Oracle error. Contact Oracle support'
Although Oracle will tell you that this is not allways a bug, in 80 to 90% of the situations that is considered to be a bug

Regarding the import
SYS is NEVER imported even with full import
SYSTEM is imported however, so you should do something about that.
I think you can specify list of users to import in the imp prompt

Regards
Boris