Sql 2005 - insufficient system memory to run this query

Hi,
We are getting right now following error:
We have Sql 2005 with 4 GB Memory

There is insufficient system memory to run this query.
Error: 701, Severity: 17, State: 42.

then it contains another messages like:
MEMORYCLERK_SQLGENERAL (Total)
 VM Reserved = 0 KB
 VM Committed = 0 KB
 AWE Allocated = 0 KB
 SM Reserved = 0 KB
 SM Committed = 0 KB
 SinglePage Allocator = 31280 KB
 MultiPage Allocator = 4504 KB

CACHESTORE_ related
USERSTORE_ related