problem with segmentation fault error

Hello,
I've got problem with PostgreSQL crash (today it was twice).

Usually, average load5 is about 16-20. Today I've run new application and load has increased dramatically.

First time before crash load was fast rising from 30 to 70 (log below)
2010-01-27 10:34:01 CET [3931]: [9-1] host=,user=,db= LOG:  server process (PID 24454) was terminated by signal 11:
Segmentationfault 
2010-01-27 10:34:01 CET [3931]: [10-1] host=,user=,db= LOG:  terminating any other active server processes
2010-01-27 10:34:01 CET [21906]: [1-1] host=X.X.X.X,user=pgmed,db=pgmed WARNING:  terminating connection because of
crashof another server process 
2010-01-27 10:34:01 CET [21906]: [2-1] host=X.X.X.X,user=pgmed,db=pgmed DETAIL:  The postmaster has commanded this
serverprocess to roll back the current transaction and exit, because another server process exited abnormally and
possiblycorrupted shared memory. 

Second time, load was about 70-80 and processor utilization was almost 100% from 1 hour (log below)
2010-01-27 18:46:06 CET [3931]: [16-1] host=,user=,db= LOG:  server process (PID 28357) was terminated by signal 11:
Segmentationfault 
2010-01-27 18:46:06 CET [3931]: [17-1] host=,user=,db= LOG:  terminating any other active server processes
2010-01-27 18:46:06 CET [26377]: [3-1] host=X.X.X.X,user=pgmed_app,db=pgmed WARNING:  terminating connection because of
crashof another server process 
2010-01-27 18:46:06 CET [26377]: [4-1] host=X.X.X.X,user=pgmed_app,db=pgmed DETAIL:  The postmaster has commanded this
serverprocess to roll back the current transaction and exit, because another server process exited abnormally and
possiblycorrupted shared memory. 

I have 8.4.0 version.

Do you have any idea where problem could be? Is it hardware or rather PostgreSQL configuration problem?
I'll be grateful for any help.

Best regards
PG