Never anonymous Bud wrote:

They fixed DLs of WUs,
but now none of my machines can UPload anything...

If you check the BOINC forums, it's a problem at the server end. 

2004-06-29 23:06:33 [SETI@home] Error on file upload: can't open file: %s

It means: 

The error your client got from the server when attempting to upload was: 

"can't open file: %s"