Since PortableApps first offered their version of Atomic Tanks (v3.8, I believe), I have never been able to get it to run on my XP Home SP3 system past the brief pink flash problem after which it shuts down... until now.
After searching the Internet for possible solutions to my problem, here's how I finally got it to work for me:
1. Copy the AtomicTanksPortable.ini from /Other/Source into the main AtomicTanksPortable folder.
2. Open the above file with a text editor and look for the "AdditionalParameters=" line.
3. Add the following command line options to the above line: "atanks.exe --nobackground --nothread -fs" (without the quotes).
4. Save the newly edited AtomicTanksPortable.ini file.
5. Start Atomic Tanks from the PortableApps menu and enjoy.
As always, YMMV, but if you've never been able to get Atomic Tanks to run under Windows XP, this may just be the trick to get it to finally work.