Sandboxie could not terminate programs in sandbox

[FlagJackGuy]

Hello and good day. I'll be as straightforward as I can. I really need advice on this, fellow Sandboxie-users.

I use a program for 3-D chatting called IMVU (Instant Messaging Virtual Universe). As can be imagined, it uses quite a bit of RAM when running for long periods of time. I've never had a problem from IMVU concerning viruses or malware. The reason I run it sandboxed is just in case, just an extra layer of defense.

I've been running IMVU sandboxed for about a week now, but only steadily in the past few days. Today, I was running IMVU sandboxed, and when I tried to terminate the program by right-clicking on the Sandboxie control icon, I received a notification which said something like this, "Some sandboxed programs could not be stopped." I also had Google Chrome running in the same sandbox, and it terminated Google Chrome. But IMVU continued to run. Even when I closed IMVU itself without trying to terminate it, the process continued to run on my task manager, and not even the task manager could stop it.

So, I tried to delete the contents of the sandbox. That also failed. I received a notification that said something similar to, "Some sandboxed programs could not be stopped. The contents of the sandbox will not be deleted." IMVU was using over 600,000K of RAM at this time. I was forced to re-start my computer, and once I re-started my computer, only then could I empty the sandbox.

I enjoy Sandboxie quite a bit, but I can't use it unless I know I can rely on it to terminate processes and delete contents. Perhaps my own lack of technical knowledge comes into play. Can anyone tell me why this happened and what I can do to resolve it or prevent it from happening again?

Notes: My operating system is Windows 7 Professional and a 64-bit system with a duo-core processor and 2 GBs of RAM. My Google Chrome version is 45.0.2454.99 m. My IMVU version is 522.0. My Sandboxie version is version 4.20 (64 bit).