avast shields "unreachable"

I have an old Dell Inspiron 8600, Win XP Home Edition SP2 (I tried SP3 awhile back and it messed things up so uninstalled); Zone Alarm, Avast, run CCleaner daily (all free versions) & Firefox.

Last week my computer wouldn't connect to internet so I called my ISP and we determined it was not the external DSL modem nor their connectivity, but my laptop (reinforced when it would NOT connect on wireless at library). I am working thru the awesome steps listed here at MG for malware removal (have had success with it a couple yrs ago) but have not done ComboFix yet. (I will need lots of time for that b/c last time I think it reset a bunch of stuff. Don't remember exactly.)

The only way I've found to go online in the interim is in Safe Mode With Networking. Have Zone Alarm running there but when I try to do anything w/ Avast it says shields are "unreachable." I looked thru the Programs in ZA and have enabled anything I can think of related to Avast.

What does unreachable mean in this case? A Search thru MG Malware Support forum yielded 9 threads but I didn't see much for my specific problem in any of them. Looked at avast's website but obviously I didn't know where to look or I'd have figured it out by now.

Any ideas on why they are unreachable (maybe a nun chaperoning them?) and how to get Avast running in Safe Mode til I can see about either reviving the computer or buying a new one?

Thanks for your patience.