Sorry - there's no way to tell without a huge debugging effort, one that is right at the edge a systems engineers skill set. It hinges on what memory space php5ts.dll is trying to write to AND why, and 'what is there' already. It could be a device driver, or a program that is customarily loaded on boot, or it could be reserved system memory (Windows) - This was the root of Sharley's comment, and why you can't find a straightforward solution. It could even be a CPU instruction set quirk. It clearly happens on a tiny, tiny percent of machines. The bad news is, even when you found it - there might still be no good solution.
I don't know exactly what you need from a suite like XAMMP, so its really hard to snuggest a best course.
You could try the new beta - its built differently for Windows that 1.7.2 and 1.7.3 - I don't think even the developers could tell you if it will solve your issue (as we don't know the root cause).http://www.apachefriends.org/en/xampp-beta.html
If you only need PHP and MySQL really just for local development, WAMP is very lightweight, you might try that.
Just remember all these variants come from the same PHP source in the same release version number AND because its a DLL its co-dependent on the Apache compile.
The best course is a function of what YOU want the server to do.
This thread was about a different topic (but similar) in the end he chose to install separately and left a link where he found the info - the topic also discusses all the techie issues involved. - you might find it usefulviewtopic.php?f=16&t=40499&p=168303&hilit=thesitewizard#p168303