Error with software update-please help

Hi, was wondering if someone could help me with this.

Software update gives met this error when I try to install the newest Airport update:

[update] cannot be verified and expanded correctly.
Make sure you have permission to write to /tmp/501/TemporaryItems/com.apple.SoftwareUpdate, then try again.

I've tried repairing permissions and running the sudo periodic maintenance scripts. I've also checked the disk using disk utility, it said a minor repair was done.

Any idea what could be wrong? I've never seen this error before.

Thanks for the input.

10.3.5 pb 12 1 ghz, 512 mb

thecow said:

download it directly from apple's site.

Click to expand...

I understand that that's the quickest solution, and I have downloaded it there, I'm just wondering as to why my software update does not work. It gives me the same error with all updates that I try now-none of them work.