I'm trying to upgrade/migrate our Joomla 1.5.23 to 1.6 or 1.7 using the Jupgrade 1.2.2 tool.

I'm about to give up as I simply can't even get the upgrade tool to do anything!

If I set it to download it leaves the download progress bar blank and skip to Decompress, which goes to 100% and then stops.

If I manually download joomla and put the zip file in /tmp or /jupgrade it does exactly the same thing!

The only error I can to find is on the decompress stage:
Error : PCLZIP_ERR_BAD_FORMAT (-10) : Unable to find End of Central Dir Record signature

Has anyone used JUpgrade successfully? I know it will not upgrade my 1.5.23 properly but it would be a good head start.