Further to my original post, I thought I would add the text from the CP.
2:19:30 PM [main] Initializing Control Panel
2:19:30 PM [main] Windows Version: Windows 7 Professional SP1 32-bit
2:19:30 PM [main] XAMPP Version: 5.5.33
2:19:30 PM [main] Control Panel Version: 3.2.2 [ Compiled: Nov 12th 2015 ]
2:19:30 PM [main] Running with Administrator rights - good!
2:19:30 PM [main] XAMPP Installation Directory: "c:\xampp\"
2:19:30 PM [main] Checking for prerequisites
2:19:49 PM [main] All prerequisites found
2:19:49 PM [main] Initializing Modules
2:19:49 PM [main] The FileZilla module is disabled
2:19:49 PM [main] The Mercury module is disabled
2:19:49 PM [main] The Tomcat module is disabled
2:19:49 PM [main] Starting Check-Timer
2:19:49 PM [main] Control Panel Ready
2:19:54 PM [Apache] Attempting to start Apache app...
2:19:54 PM [Apache] Status change detected: running
2:20:13 PM [Apache] Status change detected: stopped
2:20:13 PM [Apache] Error: Apache shutdown unexpectedly.
2:20:13 PM [Apache] This may be due to a blocked port, missing dependencies,
2:20:13 PM [Apache] improper privileges, a crash, or a shutdown by another method.
2:20:13 PM [Apache] Press the Logs button to view error logs and check
2:20:13 PM [Apache] the Windows Event Viewer for more clues
2:20:13 PM [Apache] If you need more help, copy and post this
2:20:13 PM [Apache] entire log window on the forums
Between the 2:19:54 and the 2:20:13 entries, the Windows Apache failed pop-up occurs.
From the apache_start.bat the only text that appears (in German and English) is 'Please close this command only for Shutdown. Apache 2 is starting...'. Then the Windows 'Apache HTTP Server has stopped working' etc and when the program closes the Command window disappears.
The Windows log on the General tab follows:
Faulting application name: httpd.exe, version: 22.214.171.124, time stamp: 0x561cc534
Faulting module name: libapr-1.dll, version: 126.96.36.199, time stamp: 0x561cc6a2
Exception code: 0xc0000005
Fault offset: 0x00011fcb
Faulting process id: 0x14e4
Faulting application start time: 0x01d1857dc9c53cc4
Faulting application path: C:\xampp\apache\bin\httpd.exe
Faulting module path: C:\xampp\apache\bin\libapr-1.dll
Report Id: 0a03d1a6-f171-11e5-81bc-000d613fb08d
Starting the httpd.exe directly opens a Command window that stays open until the Windows pop-ups are finished with, but no text or commands appear.
This is probably as much light as I can throw on the problem at the moment but if there is anything else that might be of use, please let me know.
Thanks in advance for any assistance.