I'm having the exact same problem as stated above.
I can't visit a page where I have to log in.
Like Hotmail, Gmail, Facebook...
Measures taken so far:
1) Flushdns (no reaction)
2) Remove all plugins (no reaction)
3) complete removal and reinstallation of CD, includig registry entrys. (did work for a while)
4) total desparation for having to use IE;
I found this thread: http://forums.comodo.com/empty-t81905.0.html;msg584609
there problems are identical to mine, but I can't figure out their solution.
And another strange thing: I'm not using Comodo proxy, which should mean I shouldn't worry about the system being down.