You will find that you can not delete entries from system tables. They have special protection. You need to use specific utilities (such as DDL statements) to have any impact on these tables.
But we have established already that you ought not to need to do so, since the project exists (as a directory) and the system tables appear to be intact. Or are you telling us that such is not the case?
Did you try reindexing the project?
IBM Software Services Group
Any contribution to this forum is my own opinion and does not necessarily reflect any position that IBM may hold.
You need to check in your project and see if those "D_" files mentioned exist or not or have a permissions problem. If they are gone for some reason, they can be copied in from any other project as they are generic files.
-craig
"You can never have too many knives" -- Logan Nine Fingers