Hoayfern;
I'll try to paraphrase here. The system registry is the command center of windows.
you can make changes on how windows runs and shut down programs and applications that are causing problems but at the same time you can render your system totally inoperable by one single mistake. To access the system registry
it's start/run/type msconfig in the block, click run, and the control panel will appear.
I know this may be a long shot but this may work also: If possible zero out your hard drive. That means writing zero's to it. the information on it is totally wiped away. In the past, an error with windows I had was not repaired with a reinstall. I had to load the HD software, zero out the drive, reformat, partition, and only then did windows run with no problems. It seems that the formatting does not clean the hard drive. It only wipes the file allocation table (FAT) that tells the system where the information is. A reinstall only puts the information back in place and does not alter windows files on the disk prior to the install.
I know I said a mouthful but I hope that this helps you. Take it slow and easy in the registry and read the help files on it.
Good Luck!