Upgrading Drupal

In the process of upgrading from 5.1 to 5.2 I somehow mistakenly turned on my theme prematurely, and didn't leave it in something like Garland, as the upgrade directions say.

The resulting problem is the infamous White Screen of Death.

How do I know it's the theme that's caused this problem? Well, I don't know with absolute certainty, but it sure looks like it. That's because I did a test. I set up another install of Drupal 5.2 on the same server. I All was working fine until I turned on my theme, which by the way, is a modified version of Lite Jazz.

My hosting service has just upgraded to PHP5 - since when I find it impossible to login to my Drupal 4.6 sites: I login, but as soon as I go to another page, the login "drops" and it is impossible to administer anything or create content. My Drupal 4.7 and 5.1 sites seem to work fine.
Is there anything I can do about this without returning to PHP4 on the servers?

Ok, I've seen a lot of posts about .htaccess files for 4.7.x releases in the /files directory. There is no mention of this in the 5.2 INSTALL.txt. Are these files required. They looked something like ...

SetHandler Drupal_Security_Do_Not_Remove_See_SA_2006_006
Options None

RewriteEngine off

Also, what did the RewriteEngine off prevent? Just curious.

Hi
I upgraded Drupal from 5.1 to 5.2. and Localizer to 5.x-2.x-dev (2007-Jun-19)
When I try to translate menu from one language to another, I get the following error:

I recently upgrade from 4.7 to 5.2. And all went well except for one thing.
I have a page that uses Javascript to enable video uploading functionality via Video Egg. It worked before the upgrade but now after the upgrade I get the IE error "cannot display this website, operation aborted" error. Only on this one video upload page.

I did some research, and have read that the general solution is to execute your code when page is loaded.
My node is a page using php code as input filter.

I've just updated from Drupal 4.7 to 5.2, and I've started to see this strange watchdog error I've never seen before. It just says:

i am new leave me alone

Which is not very helpful. A search of this site fails to find this string.

What does this message mean?