CHK Error / Illegal Operation


Andy Holmes

I’m running a G4 400 (currently on )S 9.1), 20GB system HD, 20 GB work HD, connected with SCSI scanner, USB printer, firewire 120GB HD and a broadband connection (through a hub with a firewall).

I randomly (sometimes a week, sometimes a month) have my system crash and upon restart the either of the following error screens appear: CHK Error / Illegal Operation.

The crashes seem random - hence don’t seem related to a specific program.

I am told by Apple that this may be due to OS 9.1 not coping with broadband / several connected divices very well hence I upgraded to 9.2.2 - and again the system went down.

My only solution is to perform a clean install along with all my software which is very frustrating and I am now running out of validations for some of my software.

If anyone can shed any light on these errors and more importantly what causes them I’d be very grateful. Alternatively if you could point me in the direction of any forums online as I have had limited finding indepth useful information on this particular problem.



Retired Staff
Dec 24, 2002
Reaction score
Los Angeles, California
Your Mac's Specs
14in MacBook Pro M1 Max 32GB 2TB
Have you tried the Apple discussion boards. For me it has been a long, long time since I use OS 9. Your problem could be a extension conflict. Because you upgrade to 9.2.2 the applications did change. it is possible that the problem followed you when you upgraded. But I have not used OS 9, in a while I am makeing a guess.

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