Can't delete file I own on Linux
Solution 1:
You have no write access on that directory.
dr-xr-xr-x 3 matt pg104272 4096 2011-01-27 10:37 .
You can't delete a file within a directory you don't have write access to. Moreover, quoting the Ubuntu Community manual, "write access for a directory allows deleting of files in the directory even if the user does not have write permissions for the file".
Obtain write privileges, then you're good to go.