I installed a bunch of Windows updates a few days ago, including an nVidia graphics driver via Windows Update. When I tried to run Syobon Action in Hourglass (r39 first, then r49 when I noticed there was a new Hourglass version) today (to play back anothers' .wtf file), it froze on frame 4, with a blank white surface displayed in the Syobon Action window. The frame counter was stuck on frame 4 despite Hourglass saying "Current status: Playing".
Syobon Action ran normally without Hourglass for me. I tried the same with Cave Story, and it wouldn't run either. The only game that would run in Hourglass was IWBTG, which played the entire glitched TAS WIP and synced perfectly.
I just uninstalled my nVidia graphics driver then tried Syobon Action in Hourglass again. This time, the frame counter got past frame 4 and ran quickly, but I couldn't see or hear anything (makes sense). I'll now try installing an older version of the nVidia graphics driver. If it doesn't work, I'll post an Hourglass log here.
Edit: For the record, the previous driver I had before the update was version 266.58. The version I got from the update a few days ago was version 275.33. I'm now installing version 266.58 again. I hope it works.
Edit 2: Yup! That was the problem. Going back to version 266.58 (as found from
the nVidia driver archive search) worked. Syobon Action now runs in Hourglass for me again. Unfortunately, I accidentally overwrote the Hourglass log I had with version 275.33 of the driver. I've now edited the title of this thread to reflect my findings.