Thread: server closed

does anybody know why I get the following message:

psql:1: message type 0x44 arrived from server while idle
psql::1: server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.
psql:1: connection to server was lost

I try to overlap two geometrys:

select pol.the_geom as polgeo, cc.the_geom as lpgeo from Polygons pol, CompleteChain cc where pol.the_geom && cc.the_geom;

In Relation CompleteChain are 198017 tupel and in Polygons 58063.
Are that too many tuple for about 1GB RAM and 2GB Swap?
And how can I find out the maximum number of tuple for doing such queries?

Thanks
Guido Staub