Screen resolution issue.

I have a intel, white, iMac 10.4.4 with one HD partitioned in two equal sizes. The main side resolution has changed and I cannot rest it. Each icon of a folder, on my desktop, measures about 2". If I reboot on the backup partition, then all is well. I have done LOTS of research for the last 7 hrs and cannot find a fix. The resolution that is now the default, is much larger than any option in DISPLAY.

I have
reset the PRAM and
run DisK utility
I have trashed the DISPLAY folder, and replaced it with the Display folder from the "good" partition. I also trashed a USER-Library- System folder and rebooted...

When the computer first reboots, all icons and menu bars are the correct size for a very brief moment, then it goes to the extra-large size.
I do not want to lose everything and re-install the software. Please email me directly. I have not set up email on the working drive, but I can get emails on my Blackberry and I am anxious for a solution. I am not that bright, so please be specific. Curt@PlantationPhotography.com