invalid byte sequence

After upgrading to pg 9.0.3 (from 8.4.2) on my Mac OS 10.6.2 machine i find this in my log file (a lot):

<postgres%192.168.254.210%2011-03-03 16:37:30 CET%22021>STATEMENT:  SELECT
pg_file_read('pg_log/postgresql-2011-03-03_000000.log',250000, $ 
<postgres%192.168.254.210%2011-03-03 16:37:32 CET%22021>ERROR:  invalid byte sequence for encoding "UTF8": 0xe3bc74

Apparently pg doesn't like the contents of that logfile.
The folks from the pgadmin list (i noticed the problem using the pgadmin logviewer and asked for help there) advised me
tochange LC_messages locale to 'C' (i had it on 'de_DE-UTF8' before), but that doesn't appear to help. The Server
encodingis UTF8. No special client encoding is set. 

Any help would be appreciated,

Max

Maximilian Tyrtania Software-Entwicklung
Dessauer Str. 6-7
10969 Berlin
http://www.contactking.de