I tested it on the freshly installed Joomla 2.5.4 on Linux
Do not even bothered to put in Windows - the same result

My steps to reproduce the "error"
1. I installed the new version CoreJoomla API after removing CoreJommla-JQueryPlugin.
2. Removed old version of Community Polls
3. Then setup a Community Polls RC1

Now let's talk about the errors!
1. Error "404 - An error has occurred. Component not found. Return to Control Panel". This happens when you call the menu "Components-> CoreJoomla API"
OK. Maybe this is normal?

2. When you call the menu "Components-> Community Polls" I'm getting - "CJLib (CoreJoomla API Library) component not found. Please download and install it to continue."

3. From FrondEnd when I go to the menu "Community Polls Home" - exact same error as in the previous

Sorry, but how this product can be called a Release Candidate???