You don't have permission to access /downloads/Altirra-2.50.zip on the virtualdub.org website. Nuts.
Note that if you received this error from another website, it most likely means that the other website has a crosslink to files here -- virtualdub.org is configured to reject such requests to conserve bandwidth and so people see warnings and notices I post regarding the files. DNS configuration errors sometimes also result in incorrect domain name aliases pointing here. If either of these reasons is the case, please use the correct download link from a virtualdub.org page to download the file. Thanks.
Questions? Start with "phaeron", add an @ sign, then "virtualdub.org" and use the result to drop me a note.