WordPress announced the availability of version 2.8 recently. I normally do not upgrade to the latest version as soon as it is available. One of the main reasons for not upgrading immediately is that my blog runs on the support of a lot of plugins, and an upgrade means a lot of testing, as some plugins may just refuse to work !
As a general practice, I wait for a couple of weeks before upgrading after any major release from WordPress, this will give me an overall view of the possible problems people are facing and also gives time to the plugin developers to upgrade their plugins to the work with the latest version. This way, I save a lot of time, which otherwise would be spent on trouble shooting the problems and trying to fix them.
As expected, the new version of WordPress 2.8 has crashed a few plugins and slowdown others (again performance and non compatibility issues) and the wordpress forums were filled with questions on ‘how to solve this, or I have this problem’ kind of posts. One simple solution to most of your problems is, revert back to the previous version of WordPress which was working fine (I’m hoping here that you have the back up of your database saved on your local machine !).
Those who wish to revert back to WordPress 2.7 from wordpress 2.8, please read Keith’s post, where he has explained in detail the step-by-step procedure that has to be followed.
Hope you get your blog back to life and get it to work smoothly as before.
Related Post: When is the right time to upgrade WordPress.