I also had the problem of my W7x64 system suddenly refusing to print Word documents, this I beleive began after the Office 2010 suit updates of about 10 days ago. As I dug around to find the solution I found the printer responded normaly to print instructions
from email (hotmail) and all other sources. The printer was shown as the default printer etc, adding it had no effect. I did find the "Active directory domain services is currently unavailable" message coming up as the only automated help.
When reading this thread the reference to Comodo caught my eye as I have this installed with Defence + set at safe mode. I turned Defence + off and printing from Word returned as normal. I tried Defence + at clean mode level and Protected COM monitoring
off and Word printing continues to work normally. It seems to me that the Office updates made changes that trigger blocking by Comodo defence+.
In my case Winword .exe was entered as a trusted file so cannot be entered again.
Many thanks to all you guys who have shared your insights on the forum. Thanks to you I still have a few handsful of hair that has not been torn out.