Help with kernel and possible power supply problem

Question

From 2 days after getting my imac I had my first Kernel restart.  Since then I have done everything apple has asked.  Ram resets and removing everything from the imac itself To find that it still had a kernel problem.  The error messages are Plugnplay or spinlock usually but have also been various ones such as  Kerneltask.  I have done a full reinstall of the operating system and only installed official apps from apple store, adobe flash and silverlight and next day was a kernel error for plugnplay.
The imac is currently in the shop for a look at but 2 phonecalls back saying they have had no evidence of errors. In fact its perfect for them.  The kernel is usually a few hours from turning it on but can go all day fine But they have had the imac almost a week.
So the only thing I can think of is if it works great for them is either they are really lucky or have a different electricity supply/cable.  So this leaves me thinking as stupidly as if it is working perfect for them then could it be a surge protector or power supply causing the random crashes?  Even something to do with the power lead itself?  I am really pulling at strings and going crazy because the only other thing I have been told to do is spend a week at a time just adding one thing at a time till the error shows itself so could be months and months.
i know kernel issues are historically hard to diagnose but any help would be great.  At the moment i have a £3000 paperweight on my desk thats only turned on a few hours a day  because I have no faith in it.

Answer 1

Hi Joel,
For the external drive issue try resetting your firewire ports.
To do this, shutdown and disconnect the firewire devices from your computer and from each other if there is a chain of them. Now disconnect the power cords from both your computer and from the firewire devices. Wait fifteen minutes. Connect up again and see what happens. The FW ports on Macs have a 'self re-setting fuse" that requires all power to be removed for a period of time for re-activation.
You may also want to try a PRAM reset if that doesn't resolve the issue. Sometimes this can also be implicated in FW problems. Shut down. Hold down the command option p r keys. Now start up, keeping the keys mentioned depressed until the chimes have sounded three times.
Cheers
Rod