Crazyboot is a typical boot sector virus which corrupts diskettes due to bugs in the code.
It is only able to infect a hard disk when you try to boot the machine from an infected diskette. At this time Crazyboot infects the Master Boot Record, and after that it will go resident to high DOS memory during every boot-up from the hard disk.
Once Crazyboot gets resident to memory, it will infect practicly all non-writeprotected diskettes used in the machine. It is also a stealth virus - if you try to examine an infected boot record, it will show you the original clean one instead.
Every now and then it will display the following text:
Don't PLAY with the PC ! Otherwise you will get in 'DEEP,DEEP' trouble !... Crazy Boot Ver. 1.0
Crazyboot does not keep the partition info in it's correct place in the MBR of the hard drive. Due this, do not try to disinfect this virus with the FDISK /MBR command. F-Secure anti-virus products disinfect this virus from F-PROT version 2.22 upwards.