I am not sure what the report is showing as result in PPM, but for example, if t he report is showing a list of projects based on a certain criteria, and you are trying to export the same to an excel file and getting the problem there, then I would suggest you to check if the SRM_PROJECTS.LAST_UPDATED_BY holds the value -99 (minus 99).
Now this was just an example, to explain how you can try to check the problem. So you can find the problem records by running a query, like this:
select id, name, unique_name
from srm_projects
where last_updated_by=-99
Then update those rows like this:
update srm_projects
set last_updated_by=1
where id=(select id
from srm_projects
where last_updated_by=-99)