Well that is somewhat strange as they are the two main internet facing Shields.

Check the File Systen Shield (as that is a fall back) and see if any detections there, but I rather doubt it will have done so as the web shield really should have got in first.

Since you have done a boot-time scan then any previous shield stats would be zeroed. The network shield log is about as much use as a chocolate ashtray as far as logging information goes. But you could check the actual report files, C:\Documents and Settings\All Users\Application Data\AVAST Software\Avast\report\NetworkShield.txt or the C:\Documents and Settings\All Users\Application Data\AVAST Software\Avast\report\WebShield.txt file and see if there is anything reported there.