Hi
1673 is rather very little.
Several things... Check if you have latest SPs, Might be worth checking how much memory is free before you run the report. You might also try cretating dummy report with one dataset. The dataset will execute even if you don't have anything on the report, see if it runs without giving the error.
Regarding tweaking.... if you run subqueries (usually very slow) then usually you can tweak it :)
Regards
Emil