Same here, on my local server that I use for testing purposes before making changes to the real site.
I was trying to install 1.4.3 beta, updating from latest stable version, but setup stopped at "About to update tables".
Is the first time it happens, my local environment is windows 7 64, apache 2.0.51, php 5.3.0, mysql 5.1.36.
The only difference with the on line server is that the latter is running on linux, with a more recent version of apache.