Well, I had a bad idea I thought was a good idea (Ubuntu LiveCD in Mac)

[struggle4progress]

In another thread, I suggested using an Ubuntu LiveCD as a rescue disk for a Mac

I just tried this experimentally in my white 2009 Macbook. The LiveCD started to boot, but didn't. So after a while, I gave up on it

Now I get the broken folder (do not enter) icon on all attempts to boot the Macbook

This, by the way, was a known problem:

Topic : Macbook not booting to OS X or to OS X Install DVD
http://discussions.info.apple.com/thread.jspa;jsessionid=DB9AC71F696AC967E969DF69939EF0DE.node0?messageID=11630577?
This thread contained something that worked, but I didn't get there immediately

Here's what I tried first:

Mac OS X: "Broken folder" icon, prohibitory sign, or kernel panic when computer starts
http://support.apple.com/kb/TS1892?viewlocale=en_US#one

Resetting the NVRAM and PRAM (Command-Option-P-R on startup) didn't work; see Resetting your Mac's PRAM and NVRAM http://support.apple.com/kb/HT1379?viewlocale=en_US
Subsequently holding down x on startup didn't work
Couldn't restart with install disk: broken folder (do not enter) icon again! Cuss cuss cuss!

In the middle of that, I started in firewire target mode and copied all my work files and various dmgs over to another machine for backup

Then I tried to run Apple Hardware test (d on startup)

Intel-based Macs: Using Apple Hardware Test
http://support.apple.com/kb/HT1509

The Apple Hardware test console never appeared. But the damn thing booted in the ordinary way. I verified this by doing it several times. Yep: trying the Apple Hardware Test doesn't give me a hardware test console, but it does reboot the machine. Reset the startup disk in preferences, then rebooted normally without difficulty

[alfredo]

1. You dodged a bullet it appears

[struggle4progress]

2. Yeah. I oughta think twice before enthusiastically posting my untested ideas

[alfredo]

3. No big thing. I don't know how many times I've "killed" my

computer, but later found that I didn't.

I remember the first time my wife's computer booted into open firmware mode. Scared the crap out of her. The on off button was hung up on the case.