vibe-core sporadic internal errors

[Steven Schveighoffer]

I suspect vibe-core or event core may have some subtle bugs in them that 
are not easily repeatable, but often result in half-rendered web pages.

Has anyone else seen this? I recently updated to the latest vibe-core 
and vibe to see if the problem goes away and it doesn't. A log of the 
exceptions isn't super helpful:

```
Error occurred while accessing /management/sales/translate_option: code 
500, (Internal Server Error)
Stack Trace: Internal Server Error

Error occurred while accessing /management/sales/translate_option: code 
500, (Internal Server Error)
Stack Trace: Internal Server Error

Error occurred while accessing /management/sales/translate_option: code 
500, (Internal Server Error)
Stack Trace: Internal Server Error

Error occurred while accessing /management/sales/translate_option: code 
500, (Internal Server Error)
Stack Trace: Internal Server Error
```

I also get occasional segfaults. In the distant past, I had problems so 
frequent that the site required frequent refreshes to get to the next 
page, and some of my REST-based apps failed. But upgrading to the newest 
vibe made that much less frequent.

But still, it concerns me with the frequency that this happens. I don't 
know where to begin to debug this. I'll turn tracing on to see if it 
garners any more information.

-Steve