1. How are you connecting to the internet and to WordPress.com? The way you connect to the internet (mobile, satellite, DSL, dial-up) and to your blog, and how many proxy server jumps etc. it takes to connect can cause problems. There maybe be problems with your ISP and/or with the proxy servers. Can you access any of these directly?
http://s0.wp.com/
http://s1.wp.com/
http://s2.wp.com/

2. Are you using http:// or https:// see http://en.support.wordpress.com/https/ Try using the opposite.

3. Eaxctly which browser and version of it are you using?

4. Have you tried clearing your browser cache and cookies? http://www.google.com/support/accounts/bin/answer.py?hl=en&answer=32050

5. Is your browser version up to date? You can upgrade any browser version here. http://browsehappy.com/

6. Have you tried using the browser with all extensions amd/or add-ons disabled?

7. Do you have third party cookies enabled?

8. Do you have JavaScript enabled? http://www.google.com/adsense/support/bin/answer.py?answer=12654

9. Do you have another browser you can try?

10. You can use this link to see if your Flash is up to date. http://www.adobe.com/software/flash/about/ If it’s not up to date then this is where to download and install the latest version of Flash. http://www.adobe.com/products/flashplayer/

11. Have your tried resetting your router and modem?

12. Have you had any recent operating system and/or security program updates?
Sometimes operating system and/or security system updates can cause problems so check for known issues. When you make adjustments to your browser settings — changing privacy settings, deleting cookies or increasing security — you will need to close your window and restart the browser before those new settings become effective.

If none of the troubleshooting tips work for you then you will have to contact Staff.