hello
imac not start a blue screen and then the cursor disappears....
I did the Reset NVRAM
what else can I do?
iMac, Mac OS X (10.6.8)
Safe Boot by restarting your computer while holding down the "shift" key. Safe booting disables all nonessential processes, often times allowing you to start up when you would otherwise crash.
A corrupt cache can cause the blue screen crash. Once you restart normally, the cache will be recreated. This should take care of the issue.
http://support.apple.com/kb/HT1564
http://support.apple.com/kb/HT1455