page works on public web site, but not on my computer

I have posted the question in another thread a bit down, but only buried within the thread, so please excuse me when I ask again. I want to use some PHP code from a web site (http://www.dynamicdrive.com/dynamicindex4/php-photoalbum.htm), and I am following their instruction how to implement it. I was not able to get it to work. Then I uploaded the code to a server, and lo and behold, it does work on the server. On the public site you see thumbnails of images (never mind the junk above them), when I run the SAME html and php code on my omputer, I get a blank white page. The error log has several entries, but they are all warnings: [Tue Aug 25 18:12:00 2009] [error] [client 127.0.0.1] PHP Warning: date(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/Denver' for '-6.0/DST' instead in C:\\webdev\\rmv3\\album\\getalbumpics.php on line 11, referer: http://localhost/album.htm (this error is repeated for as many images I have in the directory that the php script is reading). Between php.ini, httpd.conf, and Windows Vista, I can't figure out where to start to diagnose this, and how. Anybody out there who can give me a pointer on how to roubleshoot this issue? I am almost ready to throw in the towel and either start from scratch (although this is alrady the second time that I have uninstalled and re-installed everything), or simply forget about php altogether. that would be a shame, though...