My colleague was trying to install SQL Server 2000 on to his newly formatted Windows Vista, which although is not a supported action we need to do it cause we still have apps running on SQL Server 2000.
But the setup program just kept dying and dying once it reached the start copying phase. This puzzled me since I was able to install it.
I then noted that he had already installed VS2k5, and SQL 2k Express as well. On a hunch I told him to reformat and reinstall Vista (to clear off all remanants of anything that might have stopped the install) Luckily Windows Vista installs pretty fast so it wasn't too much of a hassle.
After the reinstall, the first thing we did was to install SQL Server 2000.. and BOOM.. it just went in..