Oh dear i need help :O(

[odin]

Try booting from the HD in question without Startup-Sequence from the Early Boot Menu (hold down both mouse buttons).

Then type 'cd s:' then 'ed startup-sequence'.

Now you can edit the s-s line by line with the Amiga's most awful but least demanding text editor :-).

-edit-
Redrum was faaaaaaaaaaaAAAAAAAAster ;-).

[odin]

From here: 'If there is something wrong with your system you may see the following colours.

    * Red: An error was found in the ROM.
    * Green: An error was found in Chip ram.
    * Blue: An error was found in the custom chips.
    * Yellow: The CPU has found an error before the error trapping software (Guru) has been activated.

These problems could be caused by a number of things such as a loose chip or board. The red screen may be caused by a loose Kickstart chip that can be fixed by pressing down on the ROM to check it is fitted correctly. Another cause could be a connection problems between the chip and socket that can be solved by straightening an bent pins. Alternatively, the green screen could be caused by a loose memory board, SIMM, or a loose RAM chip on the memory board. If reattaching these chips do not solve the problem, try them on another Amiga.'

[odin]

If there's something loose(ish) it will result in very erratic behaviour I'd say (just like human beings :-P). Loose IDE cable and/or powerflyer perhaps? (Assuming we're discussing the setup in your setup).