2 questions-

I am modeling a poly car. From time to time I convert it to sub-d to see the progress. I have started facing 2 problems-

A- When I convert to sub-d the model dissapears :O
In the scrip editor I see this. It was working fine until this moment-

// File read in 2 seconds.
select -r polyToSubd38|polyToSubd1|polyToSubd1 ;
doSubdivCreate( "2", { "1","1","3000","32"} );
deleteInternalValence2Verts |polyToSubd38|polyToSubd1|polyToSubd1|subdTessShap e3;
polyToSubdiv -ap 0 -ch off -aut on -maxPolyCount 3000 -maxEdgesPerVert 32 |polyToSubd38|polyToSubd1|polyToSubd1|subdTessShap e3;
// Warning: Nothing is selected. Select objects or components to delete. //
// Warning: Node 'polyToSubdShape40.instObjGroups[0]': cannot make assignment to 'blinn5SG' shader. //
// Error: Connection not made: 'polyToSubdShape40.instObjGroups[0]' -> 'blinn5SG.dagSetMembers[-1]'. Source node will not allow the connection. //
// Warning: Node 'polyToSubdShape40.instObjGroups[0]': cannot make assignment to 'blinn5SG' shader. //
// Error: Connection not made: 'polyToSubdShape40.instObjGroups[0]' -> 'blinn5SG.dagSetMembers[-1]'. Source node will not allow the connection. //
// Result: polyToSubdShape40 //
delete |polyToSubd38|polyToSubd1|polyToSubd1|subdTessShap e3;
// Error: More than one object matches name //???
Can you explain what I need to do?

B) When I convert the model to sub D I have in the option box "keep original unchecked". So on converting to sub-d I have just the sub-d model left. > BUT if I undo by pressing Z I get back the poly object but with sub-d copy attached to it.
Then there is nothing I can do to delete the sub-d object even if I look for it in the outliner. It's as if they are both attached at the hip. This does not happen always but only sometimes. Any idea?

Thanks