I downloaded the self extracting proTeXt.exe file from http://ftp.sun.ac.za/ftp/CTAN/systems/windows/protext/ which finished after quite a while in Windows Vista. It went on well until almost the end of extracting and I got this:
**Error encountered while performing the operation Look at the information window for more details**
Details on the information window was as follows:
Extracting MiKTeX/tm/packages/ltxbase.tar.lzma MiKTeX/tm/packages/ltxbase.tar.lzma The archive is either in unknown format or damaged The archive is either in unknown format or damaged The archive is either in unknown format or damaged ...
The version of proTeXt downloaded is 2.2.4 and seems it was downloading MiKTeX 2.9. I also ran the file as an administrator and still got the same error.