Commented Unassigned: Conversion hangs - intermittent [1854]

I installed the latest MCEB beta on a new PC a week or two ago. Worked pretty well for a while, but the last couple of days, some files are getting stuck in the conversion process. Rebooting did not fix the problem. One of these files converted successfully on a second attempt, while another failed twice but succeeded on the third try. Here's a couple of logs:

http://1drv.ms/1g2sBtZ

http://1drv.ms/1g2xlzU
Comments: ** Comment from web user: bob0909 **

.WTV file is uploading now, should be available by tomorrow:
Masterpiece Classic_KOCEDT_2014_04_06_20_59_00.wtv

Apparently Windows is lying, because I definitely have version 8.1 installed:
- I installed the upgrade from 8.0 to 8.1 myself just a couple weeks ago. It took over an hour, and completed successfully
- I see version 8.1 in Control Panel
- I have the Windows 8.1 Start button, which does not exist in Windows 8.0
Is it possible that this version discrepancy is causing a problem?

Thanks,