Could not read - Permission denied

Henrique Engelmann <henriqueengelmann@yahoo.com.br> writes:

We�re running 8.0.4 in a Windows XP box and some of the applications are not working...

Searching pg_log we�ve found the following messages:
2005-12-17 07:26:54 ERROR: could not read block 3 of relation 1663/17253/104561: Permission denied
2005-12-17 09:26:11 ERROR: could not read block 3 of relation 1663/17253/104561: Permission denied

What can be causing this error?

We've heard of misbehaving "antivirus" products causing this sort of
problem on Windows. What do you have installed on that machine?

regards, tom lane