Apple FCPX OpenGL error 506 workaround

From time to time, FCPX 10.1.1 gets stuck rendering.
The background task hourglass is stuck in a 0% - 100% loop and nothing happens.
Up to now I had to restart each time this happens (several times a day) to get out of the dreaded loop.

For info, when force-quit Apple report says:
"Final Cut Pro[1385]: *** OpenGL error 0x0506 (invalid framebuffer operation) in function "GL_CHECK_CURRENT_ERROR"

This morning after getting stuck again, I clicked: Modify/ Render selection.  That got FCPX out of stuck mode and to render normally again!  No need to force-quit/restart!
So this might be a workaround until the problem gets fixed in future version.  Make sure that something is selected in the timeline/project. Shortcut: Control + R

--- Update (March 20):
It does not always work unfortunately, if I react took late, I cannot get out of the loop.
The weird thing is that sometimes several hours pass before I get the dreaded loop. And then it happens a lot. After a while, it does not appear again.  I can't figure a reason yet.

--- Update (April 23):
I've now worked several days and the dreaded loop has not showed up. ;)   Same project(s).
What's different?
- I moved all the media outside of the FCP bundle.
- I also purged a bunch of old rendered files.
- I moved all the media and the FCP bundle to a larger Raid drive. It was a similar Raid before, but smaller, with only a few 100'sGB of free space left. Now I have several TBs of free space.

--- Update (May 9):
Alas... It's creeping back. Again I've been crippled by this error. Not sure why or when this happens. There is nothing in particular that I can pinpoint as the culprit.
If only I could use my Control + R in time, but I'm usually too late.  Cringe, cringe.

--- Update (much later)
Someone is asking if I figured this out... I don't remember!...

Since then I swapped my MacPro 3,1 for a MacPro 5,1 and all is fine.  I also upgraded to newer OsX (from Mavericks to Yosemite) and newer FCPX versions.

I believe upgrading FCPX to 10.1.2 and subsequent versions, and upgrading the OsX got me out of trouble on the MacPro 3,1: Yosemite=good, Mavericks = bad.

Another thing for sure is that I turned background rendering OFF in FCPX and that is now my default setting. This probably helped as well, or at least it sorts of became a non issue.

Let us know how it goes for you, and list your specs in the comments.
Thanks!