amiga mouse causing system to crash

[amiga4000freak]

Here i have a amiga 4000 030 revision b motherboard.
When powering her up is fine just when it shows insert disk screen i move the mouse and it starts to crash ending up with guru error code 8000 0004 saying software failure task 07c03270.  It loads up fine even with hardrive attached just when i move the mouse i get there problem.  Any ideas would be usefull

[amiga4000freak]

hello

whats happening is i cant boot there system up unless i have the mouse in its port and i cant move it otherwise it will reset itself again. i have used another mouse and the same thing happens.

[amiga4000freak]

Found out that the u975 chip is responsible for controling there mouse and when there as been a battery leak it can damage the chip so will be replacing it if i can find out where i can get hold of one if anyone knows?.