Upgrading Drupal

Hi all, I just recently upgraded from 5.3 -> 5.6 and notice that my Who's Online block is no longer accurate.

I have it set to show only those within the last 15 minutes of activity, yet some member names remain in the list for hours after they've left.

Is there a table I should empty (or check) or maybe another suggestion of where to look?

Thanks,
Brad

I currently use Drupal 5.1 and would like to introduce a Forum module.
Do I need to upgrade to version 5.6 to protect against security vulnerabilities associated with the forums, or am I safe using version 5.1?
I am concerned about adversely impacting custom applications by upgrading to 5.6, and want to know if the security risks make the upgrade necessary. Thanks.

I installed 5.1, which was part of a WAMP stack. After setting up the admin, running the cron, setting files and a couple of other things, I decided to go ahead and update to 5.6. When I got to step 5, remove all the old files, I kept getting a windows error that I could not delete includes because it was in use. The only thing I could see as using any part of Drupal was IE, so in spite of the instructions to keep this window open, I closed it to see if that would fix the problem. It did not. Then I tried stopping Apache and Mysql, but that didn't work either. I ended up having to download sysinternals process explorer to find out notepad.exe still had common.inc open even though that was yesterday and notepad itself was not open. Now I was able to delete the old files and move in all the new files. I ran update and it said it went ok. Then when I logged in, (the Drupal site was offline) I kept getting 'page not found'. I ran several searches here on the Drupal.org site but could not find anything exactly on point, and then I realized I needed to start apache and mysql again.

I've just upgraded my drupal-site to the newest stable release.

Everything went smoothly, except for the fact that my images can't be shown.

Info on the galleries remain correct, all files are present but I get the warnings:

Ferie i Boegebjerglund med Anna og Ryan (183)'s original derivative image was missing. The derivatives will be rebuilt to regenerate it.
Ferie i Boegebjerglund med Anna og Ryan (183)'s thumbnail derivative image was missing. The derivatives will be rebuilt to regenerate it.
Ferie i Boegebjerglund med Anna og Ryan (183)'s preview derivative image was missing. The derivatives will be rebuilt to regenerate it.

and

The derivative images for Ferie i Boegebjerglund med Anna og Ryan (183) have been regenerated.
warning: Division by zero in /customers/humsk.dk/humsk.dk/httpd.www/includes/image.inc on line 125.
warning: imagecreatetruecolor() [function.imagecreatetruecolor]: Invalid image dimensions in /customers/humsk.dk/humsk.dk/httpd.www/includes/image.inc on line 238.
warning: imagecopyresampled(): supplied argument is not a valid Image resource in /customers/humsk.dk/humsk.dk/httpd.www/includes/image.inc on line 264.
warning: imagejpeg(): supplied argument is not a valid Image resource in /customers/humsk.dk/humsk.dk/httpd.www/includes/image.inc on line 339.

I have inherited a Drupal system version 4.6.5

A recent update of PHP to version 5.2.5 by the host ISP caused a number of problems most of which have been solved (topics 210286 fixed via forum response, 210489 fixed by ISP and unrelated to Drupal, and 210448 partially fixed by forum).

Thanks to forum members who provide solutions or links to solutions.

It seems that the system is overdue for an update to a more recent version.

Hi there.