Permission denied on relation

I have PostgreSQL 8.0.6 running on Windows 2003 Server.

A few days ago I noticed that my logs are getting filled pretty fast.
When I checked the issue, I noticed that every one second I get the
same error as follows:

2006-01-17 05:07:38 ERROR:  could not open relation 20321/20322/796354:
Permission denied

And then every once in a while I get the following error repeated for a
few minutes every second:

2006-01-17 07:27:19 ERROR:  storage sync failed on magnetic disk:
Permission denied
2006-01-17 07:27:20 LOG:  could not fsync segment 0 of relation
20321/20322/797767: Permission denied

However when I look for those entries in the pg_class I can't find
them. They don't exist anymore. What could be the cause of these errors
and where are the relations corresponding to those numbers?

Thanks.