That's an odd message, if you are reporting it verbatim and you do not have Zone Alarm. The legitimate Zone Labs component is named "
True Vector Internet Monitor, and its process is "
vsmon.exe". Either something else is going on, or, since you say it began with the installation of Comcast cable broadband, its possible Comcast's included software incorporates a version of Zone Alarm - possibly a re-branded Zone Alarm free. I'm not aware of Zone Alarm or a derivitive used by Comcast, but that just means I'm not aware of it. Some broadband providers do embed 3rd-party security/privacy software within their installation packages, mebbe its there and you just don't know it. Have you confirmed there's nothing in your Programs file which might be from Zone Labs - or perhaps something from Comcast labled to indicate it would be a firewall? I suggest you consult with their tech support (though it pretty much sucks

) to see if in fact that is the case.
More precise info regarding the "
... message from Microsoft that an error had occurred ... blah blah blah ... " would be helpful; what Microsoft component failed, bringing up the error message, and what was the error number?
What were you doing when the errors/failures occured - what other programs or applications did you have running, and did you have multiple browsers and/or differently branded browsers open at the same time -for example, several active windows open regardless of browser/version, and/or both Firefox and Internet Explorer running at the same time? Did you have a media player active, or a graphics or text viewer/editor running? Were there any messaging or email clients open, were you downloading anything or transfering data or burning to removeable media at the time?
Please be as precise and accurate as possible when reporting error messages; they generally include useful info. If you are running a version of Windows which supports event logging (Win 9x/ME do not, without 3rd-party plugins), perhaps the message was captured by your event log, and can be retrieved from there.
Finally, what Operating System/Service Pack/Internet Explore version do you have installed, and what is the version and update status of your Firefox installation?