problems after pg_resetxlog

Hi, i had a server crash and after that , postgres refused to start, i
read on the list that pg_resetxlog could help me, indeed, after i run
pg_resetxlog dir_data, postgres started again, but i look a lot of these
errors:

CONTEXT: writing block 1 of relation 1663/17231/69118230
WARNING: could not write block 1 of 1663/17231/69118230
DETAIL: Multiple failures --- write error may be permanent.
ERROR: xlog flush request 98/E3E83848 is not satisfied --- flushed only
to 98/C364344
CONTEXT: writing block 1 of relation 1663/17231/69118230
WARNING: could not write block 1 of 1663/17231/69118230
DETAIL: Multiple failures --- write error may be permanent.
ERROR: xlog flush request 98/E3E83848 is not satisfied --- flushed only
to 98/C368658
CONTEXT: writing block 1 of relation 1663/17231/69118230
WARNING: could not write block 1 of 1663/17231/69118230
DETAIL: Multiple failures --- write error may be permanent.
ERROR: xlog flush request 98/E3E83848 is not satisfied --- flushed only
to 98/C3717F4
CONTEXT: writing block 1 of relation 1663/17231/69118230
WARNING: could not write block 1 of 1663/17231/69118230
DETAIL: Multiple failures --- write error may be permanent.
ERROR: xlog flush request 98/E3E83848 is not satisfied --- flushed only
to 98/C38554C
CONTEXT: writing block 1 of relation 1663/17231/69118230
WARNING: could not write block 1 of 1663/17231/69118230
DETAIL: Multiple failures --- write error may be permanent.

and pg_dump fails with:

pg_dump radius > radius.out
pg_dump: ERROR: xlog flush request 98/D7CFEE64 is not satisfied ---
flushed only to 98/CA37000
CONTEXT: writing block 3683 of relation 1663/17231/69127319
pg_dump: SQL command to dump the contents of table "starttelephony"
failed: PQendcopy() failed.
pg_dump: Error message from server: ERROR: xlog flush request
98/D7CFEE64 is not satisfied --- flushed only to 98/CA37000
CONTEXT: writing block 3683 of relation 1663/17231/69127319
pg_dump: The command was: COPY public.starttelephony (radacctid,
username, realm, nasipaddress, acctstarttime, calledstationid,
callingstationid, acctdelaytime, h323gwid, h323callorigin, h323calltype,
h323setuptime, h323confid) TO stdout;

what can i do?
thanks