I am receiving recurrent parser error (.NET 2.0 warning) followed by
a failure in WSS 3 search. I can't search inside of sharepoint. If
try to directly call /_vti_bin/sitedata.asmx webservice I get a
runtime error as well. These errors are logged every three minutes.
I am 110% sure that I am using a domain account to access content and
not the local service (so the KB article that mention this as a fix
is not the right one for me. This was working up until last week.

Here are the event logs

Event Type: Error
Event Source: Windows SharePoint Services 3 Search
Event Category: Gatherer
Event ID: 2424
Date: 6/26/2007
Time: 9:00:01 AM
User: N/A
Computer: SERVERNAME
Description:
The update cannot be started because the content sources cannot be
accessed. Fix the errors and try the update again.

Context: Application 'Search', Catalog 'index file on the search
server Search'

For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.