I can't reproduce this on my fairly similar system.

Are we talking about the same values of $ggg here for all invocations?

Have you made sure the sysopen variant fails consistently? How many times did you try, under what circumstances? Was this the only thing you changed in your code and its environment (such as user ID etc) between test runs?

I know these questions are fairly basic, and I didn't initially reply because I have no idea why it would fail. I was hoping that someone else would be able to pinpoint the issue. However, since there doesn't seem to be anything in your code that explains the failures you're experiencing, I guess we need to go looking elsewhere instead of guessing blindly (and badly (including not reading the question)).