After I upgraded to FF 11 I can't type Vietnamese accent anymore. It's the same installation for as long as I remember. I wonder if I just installed Comcast Guard and Norton so they tried to intercept Unikey and consider Unikey as keyboard capture.

I spent a bit on this issue and found out that the Comcast Identity Guard has blocked Unikey as it thinks Unikey is doing keyboard capture. When I disabled this feature of Comcast Guard then I can type accent in FF.