Yea 12k is like a super computer. You are probably having problems running 05 because you have an older card which might not be able to run all the features/tests.
If you want to see what very good stock scores look like than check my sig.
When I was at a LAN this past saturday this guy had just bought that exact card (X800XTPE), that was the first time I had gotten to see 3dmark05 look so smooth. Highest I've gotten in it is 3700 I believe with my 6600GT, but still it doesn't look all smooth like his did.