Will you please provide us with some details so we can try to help you?
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. It sounds like there could be a problem with your ISP. Can you access any of these directly?
2. Are you using http:// or https:// see http://en.support.wordpress.com/https/
3. Exactly 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. Do you have third party cookies enabled?
8. Do you have another browser you can try?
9. 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/