MAC won't advance to login screen from APPLE logo

[PDXMAGAZINE]

My iMAC won't advance to the login screen after I turn power on. I have tried unplugging Ethernet, all USBs, resetting PRAM (wouldn't reset), and leaving off for 10 minutes.
This all came about after I started getting a strange dialog box that said "Alert: Cannot contact Spellcheck."
suggestions?

[artov]

I had similar problem on my Macbook pro (OS X 10.5.5): I could log in, but instead of showing my normal desktop picture, the startup picture was shown and then the login screen came back. I found following url, that helped: Fixing a Mac OSX Leopard Login Loop Caused by Launch Services.

The idea is to boot using the installation DVD, go to the /Library/Cache directory (using Terminal) and remove com.apple.LaunchServices* files. The reboot using the disk. I have no idea why that helps, but it did.

[PDXMAGAZINE]

Thx Artov, I checked out the fix. I can't even get TO the login page to enter UN and PW. I basically go from hitting the power switch, to the "load" page which has a white apple logo and a gray "pinwheel of death."
Cmd-opt-esc does nothing, PRAM not affected. Haven't reset PRAM on logic board. This appears to be a software issue.
Note: Again, this problem came after a repeating "Alert: Cannot contact spell check" dialog box, and also after uploading an apple supported software update.

[PDXMAGAZINE]

Oh, and I am using OS X 10.5.5 if this is any help...

[fryke]

Start from the original system installation DVD by holding down the "c" key at startup and go to the Utilities menu where you'll find a harddrive utility. Use that to repair permissions on your system harddrive and also to repair the drive. Use the latter at least twice.

If that doesn't help, something's seriously messed up on your system. Should that be the case, simply reinstall Mac OS X and bring back your files from a backup.