Yes man, I'ved upgraded from vers 2.7 I think, to vers 3. But after the upgrade, i'ved have an message in the index that warning me that I have PHPMyAdmin version 126.96.36.199 and from SS 3. the minimal required is 5.3.2. I spoked to the host, and the upgrade procedure is in progress but it is in delay for weeks. I am worried because I want even the text from the pages to recover.... and I don't now what to do.
I recommend reverting back to the latest stable 2.4 version 3.0 is a serious upgrade and you won't want to do this on a live server. First download your site and setup a webserver locally, update your code, run through the massive upgrading guide for 3.0 then publish your site to the live server. I've upgraded a couple sites so far and usually need to update several lines of code or install modules (3.0 has seen several features of 2.4 spilt into modules like comments, widgets, RESTFul Service).
After I install 2.4 on my local machine and then upgrade it at 3.0, when I will move it to server, it won't work because in server I don't have that version of PHPMyadmin. I now only want to save the texts in the site... that's all. After that, I will install again Silverstripe when the moderators may upgrade PHP.
My vers now is not 3.0, it's 2.4.7, because i'ved used the backup. But the same problem (white page) persists.
Then check your error logs for the actual error message. The drupal documentation has a good article on the WSOD and some general points you can apply to this situation (http://drupal.org/node/158043/)