Xampp/Apache not working

I have Xampp installed on a dedicated drive. nothing else is installed on the drive. I have 6 different WordPress sites on my localhost. I have had all of these sites set up for several years and they all worked fine until today.

Now, for some unknown reason, 2 of the sites return an error message that Apache Server has stopped working. But it hasn’t stopped working. The two sites that have the problem have 5 pages that are just HTML/CSS pages and are not php/WordPress pages. WordPress is used for the blog component of the sites and not for the rest of the site pages. All the other, non-WP, site pages and navigation work just fine.

All the other sites also work just fine. Some of the other sites are the same type of primarily HTML/CSS pages with a WP blog, two of the other sites are full/all WP sites. all these WP localhost sites continue to work perfectly while at the same time the 2 sites deliver the “Apache HTTP Server has stopped working ” error.

Can anyone help me with this? I have no idea why this suddenly started on just two site only and how to go about trouble shooting and fixing.

Detail error message is below

Problem signature:
Problem Event Name: APPCRASH
Application Name: httpd.exe
Application Version: 2.4.3.0
Application Timestamp: 502f70a3
Fault Module Name: php5ts.dll
Fault Module Version: 5.4.7.0
Fault Module Timestamp: 505114f8
Exception Code: c00000fd
Exception Offset: 00039fa3
OS Version: 6.1.7601.2.1.0.256.48
Locale ID: 1033
Additional Information 1: 6017
Additional Information 2: 601762da363e8e683a9c7bfdb56acaf7
Additional Information 3: 35e5
Additional Information 4: 35e54b1d73852dc83ee624c1cfaccd9c