Jaguar Installer keeps locking up-Please help

do you got the hdd strap "AKA hdd jumper setting" set right is it set to single master or master/slave cofig ???. try the single master config go here to see what the settings you can use go here hdd strap settings or here they have 2 other drive types to look at what and how to set there hdd jumpers that could be what it is or could be bad ram or just not likeing osx . I used the single/master hdd setting mine is a 10 pin western digital yours could be diffrent or a diffrent brand of hdd it could work but i dunno. go into open firmware see if it will take the command init-nvram it will say ok if it does accept the command if not use reset-nvram press enter type set-defaults press enter then type reset-all press enter this will cause your system to accept the changes and it will restart then reset pram threw 3-4 start sounds then boot into the installer do a erase and install format it in hfs +

I'd probably first try doing a basic install rather than the full install. When you reach the last window before installing, there'll be a button that says "custom" or something like that at the bottom. Click on that and then you'll get a window with install options, so just choose the basic system and maybe the BSD subsystem installation, but click off all the foreign language stuff, etc. that you don't really need. When you click on any of the options, I think it tells you at the bottom what that option provides.

Have you tried starting up from an OS 9 install disk or a Utilities disk? I always keep a burned copy of a whole OS 9 HD with utility programs on a CD-R to use for rescue and fixing problems. I would normally startup from it and cleanup the harddrive as much as possible before attempting to install OS X. Sounds more like a hardware problem. Maybe a bad CD drive or the jumpers on the CD drive aren't correllating with the HD? Does the CD drive on iMacs have jumpers, I don't remember? Check to make sure there are no cuts or breaks on any of the cables. Do you have a clean OS 9 system on a HD? Maybe just try disconnecting the CD drive and see if the machine starts up from an OS 9 HD?
Do the 333mhz models require Xpostfacto for Jaguar installation?
Failing all this, I'd begin to suspect the motherboard. Sounds like you've tried almost everything else.

I'd go with the RAM. If I recall, which I may not, that model should use PC100, though a lot of folks will put in 133 since it works fine usually. I have had installs die because of 133 RAM that works just fine once the install is done. Also, OS 9 seems to have better tolerances towards old RAM. I don't know why, but of all the old iMacs that hit my bench, only a few had issues with 133 on reinstall.

yea id go with the pc100 sdram could be cause the type of ram like non ecc or non registered or see if your imac has any kind of problems with diffrent kinds of ram .cause there is diffrent kinds of pc100 are they mixed,is it overclocked have you tryed holding the cuda or pmu button for 10-15 seconds if it has one every time you change somthing always reset the pram . if none of thes works is there any firmware updates you need to put on it before you install is the vram maxed out. you just might want to try to go the xpostfacto4 route if all else fails. yea i know that osx supports the imac but you just might be a special case hell i dunno. if nothing works it could be a logic board problem if nothing works just a thought

I've heard that OS X prefers SDRAM that is 8ns or faster.

IIRC the specs Intel set for PC-100 call for 8ns RAM, even though PC-100 runs at 10ns. That is supposed to give leeway for timing issues. Cheaper PC-100 may be at 10ns, and higher quality may be at 8ns. I read this in Shriers "Upgrading and Repairing PCs (11th ed)". I could have the timing off from 12ns and 10ns...

ok try here http://eshop.macsales.com/Catalog_Item.cfm?ID=2541&Item=OWC100SD256168

this should be what you need