cant update software???

everytime i try and do a softeware update, i get this message on my g5

"Make sure you have permission to write to /private/tmp/501/TemporaryItems/com.apple.SoftwareUpdate, then try again."

and yes i have checked and have read and write permissions for the folder

I am lost

any thoughts

G90

Did you check the permissions on each of the folders?

I'd repair permissions:

Applications> Utilities> disk utility> select volume 'Macintosh HD'> repair disk permission.

it did try both of those options, but hey i will double check and do again
thanks
G90