How to fix the blank screen problem in WordPress
Sometimes it happens that after you upgrade your WordPress blog you get a blank page when you try to log in to your Dashboard.
Usually the reason for this is that some of your plugins may be incompatible with the new version of WordPress. If you haven't deactivated the plugins before upgrading you might get the blank screen.
What you can do in this case is to deactivate the plugins via FTP or by using the Files section of the Pixie control panel. First, you have to rename the plugins folder. If your WordPress files are in a folder called wordpress, for example, the path to the folder on your HostKnox account would be public_html/wordpress/wp-contents/plugins. So, using your favorite FTP client (e.g. FileZilla) or the control panel rename the plugins folder to something else (e.g. plugins_temp, plugins_hold, etc.).
Then log in to your Dashboard and after that rename the plugins folder back to its original name. Go to the Plugins section of the admin panel and activate the plugins to isolate the problematic one. There might be updates for the particular plugin to fix the problem, or you may just need to keep it deactivated.
There might be the same problem with your theme, if you're using a theme different than the one which comes with the base package (Twenty Ten), so you may try the same steps with the themes folder (public_html/wordpress/wp-contents/themes). That is if there is nothing wrong with the plugins.
During an upgrade it can also happen for something to go wrong with the uploading of the files. You can try and upload the files manually. Even if you did it manually the first time, you can try it again just to make sure. If you did it using the automatic update and you are not sure how to do it manually, check out the WordPress upgrade tutorial.