I have had a very similar problem (I use SRS Audio Sandbox too) where after a certain period of time my speakers persistently play a sound loop over and over again or stop working altogether.
First example of was when I played World of Warcraft and the ambient sound effects of birds seemed to have completely taken over my speakers and would refuse to play anything else. A quick look at the Volume Control (Sndvol, I use 64-bit Windows) and the SRS Sandbox control panel showed that indeed the sound was looping. Initially confused, I did not go further to attempt to resolve this problem so I just restarted my computer and wallah it seemed fine.
One week later, come my second problem: the sound seemingly just stopped. Randomly. It happened as I returned to my computer (I left it on while I went off and did something else for an hour or so). So I went again to the Volume Control and tried to test the sound (by clicking on the Volume Meter, you know... to make that 'ding' sound) but there was no sound at all, both from my speakers and what was displayed on my screen. Pressing the Volume Meter a bit more completely froze my Volume Control and I had to manually terminate 'sndvol.exe' from Task Manager. Attempting to run the Volume Control yielded the same results (it froze) so I just restarted my computer and it appeared to have been fixed.
Or so I thought.
Just today, the same thing happened again. This time I was seriously annoyed, so I ended up going to Control Panel and the Device Manager to see what screwed my sound up. I first suspected SRS Audio Sandbox (and I was right) so I attempted to disable it as one of my Playback devices (in 'Sound'). Guess what? That froze too. So I tried disabling the Sandbox program and shutting it down altogether. Problem not solved.
I tried then running Windows Media Player. That froze and crashed too.
I then tried running a game. So I opened Warcraft III and it just crashed. The main menu screen didn't even appear.
In a incredibly foul mood at this point, I went online and looked up this problem and apparently other people have been having this problem. SRS also apparently has crappy customer service and this problem has not been resolved. See: Customer Service FAIL, SRS Labs with SRS Audio Sandbox | I Spit Hot Fire
So my suggestion is to either deal with it unless it occurs extremely frequently or stop using the software altogether (although, one who has paid for the software like me [
] will be extremely reluctant to do so) as there does not appear to be a fix.