Persistant troubles, before and after reinstall and formatting

Question

Hi, I have a 2ghz Macbook Pro with 1gb of Ram.
Up until recently it was running the most recent version of 10.4, but one day recently a number of files were corrupted (not sure how many or how) leading to frequent startup troubles. I would start up and icons on the desktop would take longer to load, and some of them would be pixelated garbage instead of the normal icon. As well, several times it would log me out shortly after getting to the desktop and require me to log in again, after which things went 'normally', although several processes took longer than usual to run.
At first I booted up from a CD I tried running disk first aid to repair the disk and permissions. The disk checked out, but when I tried to repair permissions it gave me the error that disk first aid had lost contact, and that I should quit it and try again. This happened several times.
I attempted to upgrade to 10.5, having gotten the disk recently but not having installed yet. Halfway through the installation, a large amount of errors popped up and it was unable to finish the installation (I didn't write all the text down, I will try to record some later). Of course, after this there were more problems starting up as it only had about half of the system.
I dug out my old 10.4 disks, archived the 'new' system and restarted. I backed up important info onto my iPod and decided to do a reformat and reinstall starting with 10.4. After the format I also ran disk first aid, which found one permission to repair.
After this I restarted but got blue screens. Restarting in safe mode did not fix this. I restarted in single user mode based on an apple support article and ran a few commands (chmod and the like) and restarted. At the moment it still stalls on blue screens for a bit past the initial loading, but gets to the 'configure osx' presentation. However, once I try to select my keyboard layout as US, it hangs. I can change around the volume, screen lighting and move the mouse, but the application is no longer responsive.
Later tonight I will be attempting to reinstall 10.5 again, but at the moment any kind of further suggestions or input would be appreciated, in case it fails again. The disk I am installing from self-checks out by the way, so it doesn't seem to be that.

Answer 1

The HD is what I'm worried about, I can check the seating of the ram. I also ran Apple's hardware test earlier and everything checked out. Tonight I did a seven pass HD erase and reinstalled 10.4, then upgraded to 10.5. After the initial reinstall there were startup troubles, but it seems after the upgrade it is running smoothly for the moment.