Upgrading Drupal

I tried to update from 5.x to 6.x but nothing good came from it.... I have many problems with that ect. but I wanted to go back and I've copied the backup drupal to it's place and... On the page I see:
"by user"
and the RSS icon.
What's the problem?... I think it's about changes in the SQL base... please help me, I can't backup all the database at once but if You say which tables to create from backup I'll make it.
Thanks

After preforming and upgrade hooks are not firing and my pages are blank.

Is there any way to fix this or fix this issue in the database?

I have been using drupal for all of two weeks, I am extremely new to Drupal and PHP. After I upgraded from 6.9 to 6.10 my update.php file will no longer work, it gives me a blank screen and upon returnig to the site I receive the following error.

I'm about ready to do an upgrade. When it says remove old files, I have some additional files in my current directory that I'm not sure if I should delete. They are cgi-bin folder, a tmp folder, and a thumbs.db file. Any harm in leaving these?

Hi
I am having a huge problem with above error:
Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 53719 bytes) in .../includes/cache.inc on line 105

i have a upgrade the memory limit to 128 MB and still having this problem every time I am trying to enable any new module. It is like i have reached a maximum limit of modules, without having install at least all of the basic ones.

This evening late, I was attempting to upgrade from 6.9 to 6.10. I followed the Drupal upgrade text verbatim. Steps I took:

1. Backup database
2. Backup Drupal Directory
3. Login as user number 1
4. took site offline
5. disabled contrib modules (no custom modules)
6. Removed old files and directories
7. unpacked new files and directories
8. Copied backed up files and sites directory structure into Drupal installation directory
9. Ran http://mysite.com/update.php